how to make synthesis on research

How to Synthesize Written Information from Multiple Sources

Shona McCombes

Content Manager

B.A., English Literature, University of Glasgow

Shona McCombes is the content manager at Scribbr, Netherlands.

Learn about our Editorial Process

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

On This Page:

When you write a literature review or essay, you have to go beyond just summarizing the articles you’ve read – you need to synthesize the literature to show how it all fits together (and how your own research fits in).

Synthesizing simply means combining. Instead of summarizing the main points of each source in turn, you put together the ideas and findings of multiple sources in order to make an overall point.

At the most basic level, this involves looking for similarities and differences between your sources. Your synthesis should show the reader where the sources overlap and where they diverge.

Unsynthesized Example

Franz (2008) studied undergraduate online students. He looked at 17 females and 18 males and found that none of them liked APA. According to Franz, the evidence suggested that all students are reluctant to learn citations style. Perez (2010) also studies undergraduate students. She looked at 42 females and 50 males and found that males were significantly more inclined to use citation software ( p < .05). Findings suggest that females might graduate sooner. Goldstein (2012) looked at British undergraduates. Among a sample of 50, all females, all confident in their abilities to cite and were eager to write their dissertations.

Synthesized Example

Studies of undergraduate students reveal conflicting conclusions regarding relationships between advanced scholarly study and citation efficacy. Although Franz (2008) found that no participants enjoyed learning citation style, Goldstein (2012) determined in a larger study that all participants watched felt comfortable citing sources, suggesting that variables among participant and control group populations must be examined more closely. Although Perez (2010) expanded on Franz’s original study with a larger, more diverse sample…

Step 1: Organize your sources

After collecting the relevant literature, you’ve got a lot of information to work through, and no clear idea of how it all fits together.

Before you can start writing, you need to organize your notes in a way that allows you to see the relationships between sources.

One way to begin synthesizing the literature is to put your notes into a table. Depending on your topic and the type of literature you’re dealing with, there are a couple of different ways you can organize this.

Summary table

A summary table collates the key points of each source under consistent headings. This is a good approach if your sources tend to have a similar structure – for instance, if they’re all empirical papers.

Each row in the table lists one source, and each column identifies a specific part of the source. You can decide which headings to include based on what’s most relevant to the literature you’re dealing with.

For example, you might include columns for things like aims, methods, variables, population, sample size, and conclusion.

For each study, you briefly summarize each of these aspects. You can also include columns for your own evaluation and analysis.

The summary table gives you a quick overview of the key points of each source. This allows you to group sources by relevant similarities, as well as noticing important differences or contradictions in their findings.

Synthesis matrix

A synthesis matrix is useful when your sources are more varied in their purpose and structure – for example, when you’re dealing with books and essays making various different arguments about a topic.

Each column in the table lists one source. Each row is labeled with a specific concept, topic or theme that recurs across all or most of the sources.

Then, for each source, you summarize the main points or arguments related to the theme.

The purposes of the table is to identify the common points that connect the sources, as well as identifying points where they diverge or disagree.

Step 2: Outline your structure

Now you should have a clear overview of the main connections and differences between the sources you’ve read. Next, you need to decide how you’ll group them together and the order in which you’ll discuss them.

For shorter papers, your outline can just identify the focus of each paragraph; for longer papers, you might want to divide it into sections with headings.

There are a few different approaches you can take to help you structure your synthesis.

If your sources cover a broad time period, and you found patterns in how researchers approached the topic over time, you can organize your discussion chronologically .

That doesn’t mean you just summarize each paper in chronological order; instead, you should group articles into time periods and identify what they have in common, as well as signalling important turning points or developments in the literature.

If the literature covers various different topics, you can organize it thematically .

That means that each paragraph or section focuses on a specific theme and explains how that theme is approached in the literature.

Source Used with Permission: The Chicago School

If you’re drawing on literature from various different fields or they use a wide variety of research methods, you can organize your sources methodologically .

That means grouping together studies based on the type of research they did and discussing the findings that emerged from each method.

If your topic involves a debate between different schools of thought, you can organize it theoretically .

That means comparing the different theories that have been developed and grouping together papers based on the position or perspective they take on the topic, as well as evaluating which arguments are most convincing.

Step 3: Write paragraphs with topic sentences

What sets a synthesis apart from a summary is that it combines various sources. The easiest way to think about this is that each paragraph should discuss a few different sources, and you should be able to condense the overall point of the paragraph into one sentence.

This is called a topic sentence , and it usually appears at the start of the paragraph. The topic sentence signals what the whole paragraph is about; every sentence in the paragraph should be clearly related to it.

A topic sentence can be a simple summary of the paragraph’s content:

“Early research on [x] focused heavily on [y].”

For an effective synthesis, you can use topic sentences to link back to the previous paragraph, highlighting a point of debate or critique:

“Several scholars have pointed out the flaws in this approach.” “While recent research has attempted to address the problem, many of these studies have methodological flaws that limit their validity.”

By using topic sentences, you can ensure that your paragraphs are coherent and clearly show the connections between the articles you are discussing.

As you write your paragraphs, avoid quoting directly from sources: use your own words to explain the commonalities and differences that you found in the literature.

Don’t try to cover every single point from every single source – the key to synthesizing is to extract the most important and relevant information and combine it to give your reader an overall picture of the state of knowledge on your topic.

Step 4: Revise, edit and proofread

Like any other piece of academic writing, synthesizing literature doesn’t happen all in one go – it involves redrafting, revising, editing and proofreading your work.

Checklist for Synthesis

•   Do I introduce the paragraph with a clear, focused topic sentence?
•   Do I discuss more than one source in the paragraph?
•   Do I mention only the most relevant findings, rather than describing every part of the studies?
•   Do I discuss the similarities or differences between the sources, rather than summarizing each source in turn?
•   Do I put the findings or arguments of the sources in my own words?
•   Is the paragraph organized around a single idea?
•   Is the paragraph directly relevant to my research question or topic?
•   Is there a logical transition from this paragraph to the next one?

Further Information

How to Synthesise: a Step-by-Step Approach

Help…I”ve Been Asked to Synthesize!

Learn how to Synthesise (combine information from sources)

How to write a Psychology Essay

Literature Review Basics

• What is a Literature Review?
• Synthesizing Research
• Using Research & Synthesis Tables
• Additional Resources

Synthesis: What is it?

First, let's be perfectly clear about what synthesizing your research isn't :

• - It isn't  just summarizing the material you read
• - It isn't  generating a collection of annotations or comments (like an annotated bibliography)
• - It isn't  compiling a report on every single thing ever written in relation to your topic

When you  synthesize  your research, your job is to help your reader understand the current state of the conversation on your topic, relative to your research question.  That may include doing the following:

• - Selecting and using representative work on the topic
• - Identifying and discussing trends in published data or results
• - Identifying and explaining the impact of common features (study populations, interventions, etc.) that appear frequently in the literature
• - Explaining controversies, disputes, or central issues in the literature that are relevant to your research question
• - Identifying gaps in the literature, where more research is needed
• - Establishing the discussion to which your own research contributes and demonstrating the value of your contribution

Essentially, you're telling your reader where they are (and where you are) in the scholarly conversation about your project.

Synthesis: How do I do it?

Synthesis, step by step.

This is what you need to do  before  you write your review.

• Identify and clearly describe your research question (you may find the Formulating PICOT Questions table at  the Additional Resources tab helpful).
• Collect sources relevant to your research question.
• Organize and describe the sources you've found -- your job is to identify what  types  of sources you've collected (reviews, clinical trials, etc.), identify their  purpose  (what are they measuring, testing, or trying to discover?), determine the  level of evidence  they represent (see the Levels of Evidence table at the Additional Resources tab ), and briefly explain their  major findings . Use a Research Table to document this step.
• Study the information you've put in your Research Table and examine your collected sources, looking for  similarities  and  differences . Pay particular attention to  populations ,   methods  (especially relative to levels of evidence), and  findings .
• Analyze what you learn in (4) using a tool like a Synthesis Table. Your goal is to identify relevant themes, trends, gaps, and issues in the research.  Your literature review will collect the results of this analysis and explain them in relation to your research question.

Analysis tips

• - Sometimes, what you  don't  find in the literature is as important as what you do find -- look for questions that the existing research hasn't answered yet.
• - If any of the sources you've collected refer to or respond to each other, keep an eye on how they're related -- it may provide a clue as to whether or not study results have been successfully replicated.
• - Sorting your collected sources by level of evidence can provide valuable insight into how a particular topic has been covered, and it may help you to identify gaps worth addressing in your own work.
• << Previous: What is a Literature Review?
• Next: Using Research & Synthesis Tables >>
• Last Updated: Sep 26, 2023 12:06 PM
• URL: https://usi.libguides.com/literature-review-basics

A Guide to Evidence Synthesis: What is Evidence Synthesis?

• Meet Our Team
• Our Published Reviews and Protocols
• What is Evidence Synthesis?
• Types of Evidence Synthesis
• Evidence Synthesis Across Disciplines
• Finding and Appraising Existing Systematic Reviews
• 0. Develop a Protocol
• 1. Draft your Research Question
• 2. Select Databases
• 3. Select Grey Literature Sources
• 4. Write a Search Strategy
• 5. Register a Protocol
• 6. Translate Search Strategies
• 7. Citation Management
• 8. Article Screening
• 9. Risk of Bias Assessment
• 10. Data Extraction
• 11. Synthesize, Map, or Describe the Results
• Evidence Synthesis Institute for Librarians
• Open Access Evidence Synthesis Resources

What are Evidence Syntheses?

What are evidence syntheses.

According to the Royal Society, 'evidence synthesis' refers to the process of bringing together information from a range of sources and disciplines to inform debates and decisions on specific issues. They generally include a methodical and comprehensive literature synthesis focused on a well-formulated research question.  Their aim is to identify and synthesize all  of the scholarly research on a particular topic, including both published and unpublished studies. Evidence syntheses are conducted in an unbiased, reproducible way to provide evidence for practice and policy-making, as well as to identify gaps in the research. Evidence syntheses may also include a meta-analysis, a more quantitative process of synthesizing and visualizing data retrieved from various studies. 

Evidence syntheses are much more time-intensive than traditional literature reviews and require a multi-person research team. See this PredicTER tool to get a sense of a systematic review timeline (one type of evidence synthesis). Before embarking on an evidence synthesis, it's important to clearly identify your reasons for conducting one. For a list of types of evidence synthesis projects, see the next tab.

How Does a Traditional Literature Review Differ From an Evidence Synthesis?

How does a systematic review differ from a traditional literature review.

One commonly used form of evidence synthesis is a systematic review.  This table compares a traditional literature review with a systematic review.

Video: Reproducibility and transparent methods (Video 3:25)

Reporting Standards

There are some reporting standards for evidence syntheses. These can serve as guidelines for protocol and manuscript preparation and journals may require that these standards are followed for the review type that is being employed (e.g. systematic review, scoping review, etc). ​

• PRISMA checklist Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.
• PRISMA-P Standards An updated version of the original PRISMA standards for protocol development.
• PRISMA - ScR Reporting guidelines for scoping reviews and evidence maps
• PRISMA-IPD Standards Extension of the original PRISMA standards for systematic reviews and meta-analyses of individual participant data.
• EQUATOR Network The EQUATOR (Enhancing the QUAlity and Transparency Of health Research) Network is an international initiative that seeks to improve the reliability and value of published health research literature by promoting transparent and accurate reporting and wider use of robust reporting guidelines. They provide a list of various standards for reporting in systematic reviews.

Video: Guidelines and reporting standards

PRISMA Flow Diagram

The  PRISMA  flow diagram depicts the flow of information through the different phases of an evidence synthesis. It maps the search (number of records identified), screening (number of records included and excluded), and selection (reasons for exclusion).  Many evidence syntheses include a PRISMA flow diagram in the published manuscript.

See below for resources to help you generate your own PRISMA flow diagram.

• PRISMA Flow Diagram Tool
• PRISMA Flow Diagram Word Template
• << Previous: Our Published Reviews and Protocols
• Next: Types of Evidence Synthesis >>
• Last Updated: Apr 24, 2024 2:56 PM
• URL: https://guides.library.cornell.edu/evidence-synthesis

The Sheridan Libraries

• Write a Literature Review
• Sheridan Libraries
• Find This link opens in a new window
• Evaluate This link opens in a new window

Get Organized

• Lit Review Prep Use this template to help you evaluate your sources, create article summaries for an annotated bibliography, and a synthesis matrix for your lit review outline.

Synthesize your Information

Synthesize: combine separate elements to form a whole.

Synthesis Matrix

A synthesis matrix helps you record the main points of each source and document how sources relate to each other.

After summarizing and evaluating your sources, arrange them in a matrix or use a citation manager to help you see how they relate to each other and apply to each of your themes or variables.  

By arranging your sources by theme or variable, you can see how your sources relate to each other, and can start thinking about how you weave them together to create a narrative.

• Step-by-Step Approach
• Example Matrix from NSCU
• Matrix Template
• << Previous: Summarize
• Next: Integrate >>
• Last Updated: Sep 26, 2023 10:25 AM
• URL: https://guides.library.jhu.edu/lit-review

• How it works

How to Synthesise Sources – Steps and Examples

Published by Olive Robin at October 17th, 2023 , Revised On October 17, 2023

The ability to effectively incorporate multiple sources into one’s work is not just a skill, but a necessity. Whether we are talking about research papers, articles, or even simple blog posts, synthesising sources can elevate our content to a more nuanced, comprehensive, and insightful level. But what does it truly mean to synthesise sources, and how does it differ from the commonly understood techniques of summarising and paraphrasing?

Importance of Synthesising Sources in Research and Writing

When finding sources , it is imperative to distinguish between various available information types. Secondary sources , for example, provide interpretations and analyses based on primary sources. Synthesising goes beyond the mere gathering of information. It involves the complex task of interweaving multiple sources to generate a broader and richer perspective. When we synthesise, we are not just collecting; we are connecting. 

By merging various viewpoints and data, we provide our readers with a well-rounded understanding of the topic. This approach ensures that our work is grounded in credible sources  while also adding unique insights.

Summarising, Paraphrasing, and Synthesising

At first glance, these three techniques might seem similar, but they serve distinctly different purposes:

Summarising

Synthesis is the art of blending multiple sources to create a unified narrative or argument. It is essential to use signal phrases to introduce these sources naturally, helping the reader follow the information flow. Block quotes can also be used for direct quotations, especially if they’re longer.

Paraphrasing

Here, we restate the original content using different words. While the wording changes, the essence and core meaning remain intact. This method is useful for clarifying complex ideas or for tailoring content to a specific audience.

Synthesising

Synthesis is the art of blending multiple sources to create a unified narrative or argument. It is not about echoing what others have said; it is about drawing connections, identifying patterns, and building a cohesive piece that holds its own merit.

What is Synthesising Sources?

Synthesising sources is a method used in research and writing wherein the author combines, interprets, and analyses information from various sources to generate a unified perspective, narrative, or argument. It involves a process that we can call source evaluation . It is an intricate process that goes beyond simply collecting data or quoting authors. Instead, it involves evaluating, integrating, and constructing a new narrative based on a collective understanding of all the sources under consideration.

Imagine a quilt where each piece of fabric represents a different source. Synthesising would be the act of sewing these individual pieces together in such a way that they form a beautiful, cohesive blanket. Each piece retains its uniqueness but contributes to the larger design and purpose of the quilt.

Objective of Synthesising

• Synthesising allows writers to delve deeper into topics by using a multitude of perspectives. This offers a more robust and comprehensive view than any single source could provide.
• By integrating diverse sources, authors can identify trends, consistencies, or discrepancies within a field or topic. This can lead to new insights or highlight areas needing further exploration.
• By interlinking sources, writers can add layers of complexity to their arguments, making their content more engaging and thought-provoking.
• While the sources themselves might not be new, the way in which they are combined and interpreted can lead to fresh conclusions and unique standpoints.
• Relying on a single source or a few like-minded ones can inadvertently introduce biases. Synthesising encourages the consideration of diverse viewpoints, ensuring a more balanced representation of the topic.

Why is Synthesis Important?

The art of synthesis, while a nuanced aspect of research and writing, holds unparalleled significance in constructing meaningful, in-depth content. Here is a detailed exploration of why synthesis is pivotal:

Enhancing Comprehension and Knowledge Depth

• Depth Over Breadth: While a vast amount of information exists on nearly any topic, true understanding isn’t about skimming the surface. Synthesising allows you to dive deeper, connecting various pieces of information and seeing the bigger picture.
• Clarifying Complexity: Topics, especially those in research, can be multifaceted. By merging multiple sources, we can simplify and explain intricate subjects more effectively.
• Reinforcing Concepts: By revisiting a concept from various sources and angles, the repetition, in a way, strengthens our grasp on the subject. It’s like studying from multiple textbooks; the overlap in content solidifies understanding.

Avoiding Plagiarism

• Original Thought Generation: While synthesising, you are compelled to merge ideas, compare viewpoints, and draw unique conclusions. This process naturally leads to producing original content rather than merely reproducing what one source says.
• Skilful Integration: A well-synthesised piece does not heavily rely on long, verbatim quotes. Instead, it seamlessly integrates information from various sources, duly cited, minimising the chances of unintentional plagiarism.
• Reflecting Authentic Engagement: When you synthesise, it showcases your genuine engagement with the material. It’s evident that you have not just copied content but have wrestled with the information, pondered upon it, and made it your own.

Developing a Holistic Perspective on a Topic

• Seeing the Full Spectrum: Single sources can offer a limited or biased viewpoint. Synthesis, by its nature, compels you to consult multiple sources, allowing for a more balanced and comprehensive view.
• Connecting the Dots: Life, society, and most academic subjects are interconnected. Synthesis helps recognise patterns, draw parallels, and understand how various elements interplay in the grand scheme of things.
• Elevating Critical Thinking: The act of synthesis hones your critical thinking skills. You’re constantly evaluating the validity of sources, comparing arguments, and discerning the weight of different perspectives. This makes your current work stronger and sharpens your intellect for future projects.

Steps of Synthesizing a Source

Here is a step-by-step guide on how to synthesise sources. 

Step 1: Read and Understand

Before you can synthesise sources effectively, you must first understand them individually. A strong synthesis is built upon a clear understanding of each source’s content, context, and nuances.

Tips To Ensure Comprehension

• Annotations: Make notes in the margins as you read, highlighting key points and ideas.
• Summarisation: After reading a section or an article, write a brief summary in your own words.
• Discussion: Talk about the content with peers or mentors. This can help clarify any confusion and deepen your understanding.
• Questioning: Constantly ask questions as you read. If something is unclear, revisit the content or consult supplementary materials.

Step 2: Identify Common Themes

Sources will often touch upon similar themes, even if they approach them differently. Recognising these themes can act as a foundation for synthesis.

• Mind Mapping: Visualise the interconnectedness of topics and subtopics.
• Lists: Create lists of similar ideas or arguments from different sources.
• Highlighting: Use colour codes to highlight recurring themes across different documents.

Step 3: Analyse and Compare

Different sources might have diverging opinions or findings. Recognising these differences is crucial to produce a balanced synthesis.

• Side-by-Side Analysis: Put the information from various sources next to each other to see how they align or diverge.
• Critical Evaluation: Ask yourself why sources might have different perspectives. Consider the methodology, context, or biases that could contribute.

Determining the Relevance of Each Source

Not all sources will hold equal weight or relevance in your synthesis.

• Criteria Checklist: Establish criteria for relevance (e.g., publication date, author credentials) and evaluate each source against this.
• Priority Setting: Decide which sources offer primary insights and which offer supplementary information.

Step 4: Organise Information

A clear structure is essential to guide your readers through the synthesised narrative.

• Outlines: Create a traditional outline that sequences your main points and supports them with subpoints from your sources.
• Flowcharts: For more complex topics, flowcharts can visually demonstrate the progression of ideas and their interconnections.

Step 5: Craft Your Narrative

This step involves the actual writing, where you combine the insights, evidence, and analysis into a singular narrative.

• Transitional Phrasing: Use transitions to move between ideas and sources smoothly.
• Voice Consistency: Even though you integrate multiple sources, ensure that the narrative maintains a consistent voice and tone.

Step 6: Cite Appropriately

Always credit original authors and sources to maintain integrity in your work and avoid plagiarism. Knowing how to cite sources is crucial in this process.

• In-text Citations: Whenever you refer to, paraphrase, or quote a source, provide a citation.

Different Citation Styles and Choosing The Right One

There are multiple citation styles (e.g., APA, MLA, Chicago), and your choice will often depend on your discipline or the preference of your institution or publication.

• Guideline Review: Familiarise yourself with the preferred citation style’s guidelines.

Citation Tools: Consider using tools like Zotero, Mendeley, or EndNote to help streamline and manage your citations.

The research done by our experts have:

• Precision and Clarity
• Zero Plagiarism
• Authentic Sources

Examples of Source Synthesis

Let’s explore some examples of synthesising sources. 

Example 1: Synthesising sources on climate change

Scenario: You have sources that discuss the causes of climate change. Some sources argue for anthropogenic (human-caused) factors, while others emphasise natural cycles.

Synthesis Approach

• Begin with an overview of climate change, its impacts, and its significance.
• Introduce the anthropogenic viewpoint, citing research on the rise of CO2 from industrial processes, deforestation, etc.
• Present the natural cycle perspective, highlighting periods in Earth’s history where temperature fluctuations were observed.
• Discuss overlaps, such as how human activities might exacerbate natural cycles.
• Conclude by emphasising the consensus in the scientific community about human contributions to recent climate change, but acknowledge the existence of natural cycles as part of Earth’s climate history.

Example 2: Merging Historical Texts on a Particular Event

Scenario: You are examining the Battle of Waterloo from British, French, and Prussian primary sources.

• Provide background on the Battle of Waterloo, setting the stage.
• Introduce the British perspective, detailing their strategies, key figures, and their account of the battle’s progression.
• Shift to the French viewpoint, noting their strategic decisions, challenges, and Napoleon’s role.
• Explore the Prussian account, emphasising their contributions and coordination with the British.
• Highlight areas of agreement among the sources (e.g., timeline of events) and areas of discrepancy or unique insights (e.g., differing reasons for the outcome).
• Conclude with a comprehensive view of the battle, incorporating insights from all perspectives and its significance in European history.

Example 3: Synthesising Qualitative And Quantitative Research On A Social Issue

Scenario: You are researching the effects of remote learning on student performance and well-being during the pandemic.

• Start with an introduction to the sudden shift to remote learning due to COVID-19.
• Present quantitative data: statistics showcasing the drop or rise in student grades, attendance rates, and standardised test scores.
• Introduce qualitative insights, like interviews or case studies, highlighting student sentiments, challenges faced at home, or feelings of isolation.
• Discuss the interplay between numbers and narratives. For instance, a drop in grades (quantitative) could be related to a lack of motivation or home distractions (qualitative).
• Compare outcomes across different demographics, using both types of data to show how remote learning might affect diverse student populations differently.
• Conclude with a holistic understanding of the impacts of remote learning, noting areas that need further research or intervention.

Common Mistakes to Avoid when Synthesising Sources

• Relying heavily on a single source limits the depth and breadth of your understanding. It may also inadvertently introduce bias if that source isn’t comprehensive or neutral.
• How to Avoid: Ensure you consult various sources for a well-rounded view. This includes both primary and secondary sources, academic articles, and more accessible pieces like news articles or blogs, if relevant.
• Every source comes with its own perspective. Identifying these biases can lead to a skewed understanding of your topic.
• How to Avoid: Critical reading is key. Always consider who the author is, their potential motivations, the context in which they’re writing, and the methodologies they use.
• Simply presenting what each source says without drawing connections or highlighting contrasts misses the essence of synthesis.
• How to Avoid: As you research, actively look for common themes, conflicting viewpoints, and unique insights. Your goal is to weave a narrative that reflects a comprehensive understanding of all these elements.

Tools and Resources for Synthesising Sources

These are the different tools that can be used for synthesising sources. 

Citation Tools

Managing references can be cumbersome, especially when dealing with numerous sources. Citation tools can help organise, format, and insert citations with ease.

• Zotero: A free, open-source tool that helps you collect, organise, cite, and share research.
• Mendeley: A reference manager and academic social network that can help you organise your research, collaborate with others online, and discover the latest developments.

Mind-Mapping Software or Apps

Mind mapping helps visually organise and interlink ideas, making the synthesis process more intuitive.

• MindMeister: An online mind-mapping tool that lets you capture, develop, and share ideas visually.
• XMind: A popular mind mapping and brainstorming software with various templates to help structure your thoughts.

Note-Taking Apps and Strategies

Effective note-taking is fundamental to understanding and organising information from various sources. Digital note-taking apps often offer features like tagging, search functionalities, and integration with other tools.

• Evernote: A cross-platform app designed for note-taking, organising, and archiving.
• Microsoft OneNote: A digital notebook that allows you to gather drawings, handwritten or typed notes, and save web clippings.
• Cornell Note-taking System: A structured method of note-taking that divides the paper into sections, encouraging active engagement with the material.

Frequently Asked Questions

What is a literature review.

A literature review is a comprehensive survey of existing research on a particular topic, synthesising findings to provide an overview of key concepts, debates, and gaps in knowledge. It establishes a foundation for new research, highlighting relevant studies and contextualising them within the broader academic conversation.

How to synthesise a source?

To synthesise a source, thoroughly understand its content, and then integrate its insights with information from other sources. This involves comparing and contrasting viewpoints, identifying patterns, and constructing a cohesive narrative or argument that offers a broader perspective rather than merely echoing the original source’s content.

Why do I need to cite sources?

Citing sources acknowledges original authors, maintains academic integrity, and provides readers with a reference for verification. It prevents plagiarism by giving credit to the ideas and research of others, allowing readers to trace the evolution of thought and confirm the reliability and accuracy of the presented information.

What are topic sentences?

Topic sentences are the main statements that introduce and summarise a paragraph’s main idea or focus. They provide context and direction, helping readers follow the writer’s argument or narrative. Typically placed at the beginning of a paragraph, they act as signposts, guiding the flow of the discussion.

You May Also Like

In any form of written communication, be it academic writing, journalism, or even casual blogging, there comes a time when we need to reference another’s words to support, explain, or emphasise our points.

In today’s information age, where vast amounts of knowledge are easily accessible, it is crucial to know how to use and represent that knowledge correctly and how to cite sources properly.

Academic sources, also known as scholarly sources or academic references, are materials used by researchers, scholars, and students to support their academic work. These sources are specifically created for use in academic contexts and contribute to the body of knowledge in a particular field of study.

USEFUL LINKS

LEARNING RESOURCES

COMPANY DETAILS

• How It Works

Purdue Online Writing Lab Purdue OWL® College of Liberal Arts

Synthesizing Sources

Welcome to the Purdue OWL

This page is brought to you by the OWL at Purdue University. When printing this page, you must include the entire legal notice.

Copyright ©1995-2018 by The Writing Lab & The OWL at Purdue and Purdue University. All rights reserved. This material may not be published, reproduced, broadcast, rewritten, or redistributed without permission. Use of this site constitutes acceptance of our terms and conditions of fair use.

When you look for areas where your sources agree or disagree and try to draw broader conclusions about your topic based on what your sources say, you are engaging in synthesis. Writing a research paper usually requires synthesizing the available sources in order to provide new insight or a different perspective into your particular topic (as opposed to simply restating what each individual source says about your research topic).

Note that synthesizing is not the same as summarizing.  

• A summary restates the information in one or more sources without providing new insight or reaching new conclusions.
• A synthesis draws on multiple sources to reach a broader conclusion.

There are two types of syntheses: explanatory syntheses and argumentative syntheses . Explanatory syntheses seek to bring sources together to explain a perspective and the reasoning behind it. Argumentative syntheses seek to bring sources together to make an argument. Both types of synthesis involve looking for relationships between sources and drawing conclusions.

In order to successfully synthesize your sources, you might begin by grouping your sources by topic and looking for connections. For example, if you were researching the pros and cons of encouraging healthy eating in children, you would want to separate your sources to find which ones agree with each other and which ones disagree.

After you have a good idea of what your sources are saying, you want to construct your body paragraphs in a way that acknowledges different sources and highlights where you can draw new conclusions.

As you continue synthesizing, here are a few points to remember:

• Don’t force a relationship between sources if there isn’t one. Not all of your sources have to complement one another.
• Do your best to highlight the relationships between sources in very clear ways.
• Don’t ignore any outliers in your research. It’s important to take note of every perspective (even those that disagree with your broader conclusions).

Example Syntheses

Below are two examples of synthesis: one where synthesis is NOT utilized well, and one where it is.

Parents are always trying to find ways to encourage healthy eating in their children. Elena Pearl Ben-Joseph, a doctor and writer for KidsHealth , encourages parents to be role models for their children by not dieting or vocalizing concerns about their body image. The first popular diet began in 1863. William Banting named it the “Banting” diet after himself, and it consisted of eating fruits, vegetables, meat, and dry wine. Despite the fact that dieting has been around for over a hundred and fifty years, parents should not diet because it hinders children’s understanding of healthy eating.

In this sample paragraph, the paragraph begins with one idea then drastically shifts to another. Rather than comparing the sources, the author simply describes their content. This leads the paragraph to veer in an different direction at the end, and it prevents the paragraph from expressing any strong arguments or conclusions.

An example of a stronger synthesis can be found below.

Parents are always trying to find ways to encourage healthy eating in their children. Different scientists and educators have different strategies for promoting a well-rounded diet while still encouraging body positivity in children. David R. Just and Joseph Price suggest in their article “Using Incentives to Encourage Healthy Eating in Children” that children are more likely to eat fruits and vegetables if they are given a reward (855-856). Similarly, Elena Pearl Ben-Joseph, a doctor and writer for Kids Health , encourages parents to be role models for their children. She states that “parents who are always dieting or complaining about their bodies may foster these same negative feelings in their kids. Try to keep a positive approach about food” (Ben-Joseph). Martha J. Nepper and Weiwen Chai support Ben-Joseph’s suggestions in their article “Parents’ Barriers and Strategies to Promote Healthy Eating among School-age Children.” Nepper and Chai note, “Parents felt that patience, consistency, educating themselves on proper nutrition, and having more healthy foods available in the home were important strategies when developing healthy eating habits for their children.” By following some of these ideas, parents can help their children develop healthy eating habits while still maintaining body positivity.

In this example, the author puts different sources in conversation with one another. Rather than simply describing the content of the sources in order, the author uses transitions (like "similarly") and makes the relationship between the sources evident.

Get Started

Take the first step and invest in your future.

Online Programs

Offering flexibility & convenience in 51 online degrees & programs.

Prairie Stars

Featuring 15 intercollegiate NCAA Div II athletic teams.

Find your Fit

UIS has over 85 student and 10 greek life organizations, and many volunteer opportunities.

Arts & Culture

Celebrating the arts to create rich cultural experiences on campus.

Give Like a Star

Your generosity helps fuel fundraising for scholarships, programs and new initiatives.

Bragging Rights

UIS was listed No. 1 in Illinois and No. 3 in the Midwest in 2023 rankings.

• Quick links Applicants & Students Important Apps & Links Alumni Faculty and Staff Community Admissions How to Apply Cost & Aid Tuition Calculator Registrar Orientation Visit Campus Academics Register for Class Programs of Study Online Degrees & Programs Graduate Education International Student Services Study Away Student Support Bookstore UIS Life Dining Diversity & Inclusion Get Involved Health & Wellness COVID-19 United in Safety Residence Life Student Life Programs UIS Connection Important Apps UIS Mobile App Advise U Canvas myUIS i-card Balance Pay My Bill - UIS Bursar Self-Service Email Resources Bookstore Box Information Technology Services Library Orbit Policies Webtools Get Connected Area Information Calendar Campus Recreation Departments & Programs (A-Z) Parking UIS Newsroom Connect & Get Involved Update your Info Alumni Events Alumni Networks & Groups Volunteer Opportunities Alumni Board News & Publications Featured Alumni Alumni News UIS Alumni Magazine Resources Order your Transcripts Give Back Alumni Programs Career Development Services & Support Accessibility Services Campus Services Campus Police Facilities & Services Registrar Faculty & Staff Resources Website Project Request Web Services Training & Tools Academic Impressions Career Connect CSA Reporting Cybersecurity Training Faculty Research FERPA Training Website Login Campus Resources Newsroom Campus Calendar Campus Maps i-Card Human Resources Public Relations Webtools Arts & Events UIS Performing Arts Center Visual Arts Gallery Event Calendar Sangamon Experience Center for Lincoln Studies ECCE Speaker Series Community Engagement Center for State Policy and Leadership Illinois Innocence Project Innovate Springfield Central IL Nonprofit Resource Center NPR Illinois Community Resources Child Protection Training Academy Office of Electronic Media University Archives/IRAD Institute for Illinois Public Finance

Request Info

Synthesizing Research

• Request Info Request info for....     Undergraduate/Graduate     Online     Study Away     Continuing & Professional Education     International Student Services     General Inquiries

When combining another author’s ideas with your own, we have talked about how using the can help make sure your points are being adequately argued (if you have not read our handout on the  evidence cycle,  check it out!). Synthesis takes assertions (statements that describe your claim), evidence (facts and proof from outside sources), and commentary (your connections to why the evidence supports your claim), and blends these processes together to make a cohesive paragraph.

In other words, synthesis encompasses several aspects:

• It is the process of integrating support from more than one source for one idea/argument while also identifying how sources are related to each other and to your main idea.
• It is an acknowledgment of how the source material from several sources address the same question/research topic.
• It is the identification of how important factors (assumptions, interpretations of results, theories, hypothesis, speculations, etc.) relate between separate sources.

TIP: It’s a fruit smoothie!

Think of synthesis as a fruit smoothie that you are creating in your paper. You will have unique parts and flavors in your writing that you will need to blend together to make one tasty, unified drink!

Why Synthesis is Important

• Synthesis integrates information from multiple sources, which shows that you have done the necessary research to engage with a topic more fully.
• Research involves incorporating many sources to understand and/or answer a research question, and discovering these connections between the sources helps you better analyze and understand the conversations surrounding your topic.
• Successful synthesis creates links between your ideas helping your paper “flow” and connect better.
• Synthesis prevents your papers from looking like a list of copied and pasted sources from various authors.
• Synthesis is a higher order process in writing—this is the area where you as a writer get to shine and show your audience your reasoning.

Types of Synthesis

Demonstrates how two or more sources agree with one another.

The collaborative nature of writing tutorials has been discussed by scholars like Andrea Lunsford (1991) and Stephen North (1984). In these essays, they explore the usefulness and the complexities of collaboration between tutors and students in writing center contexts.

Demonstrates how two or more sources support a main point in different ways.

While some scholars like Berlin (1987) have primarily placed their focus on the histories of large, famous universities, other scholars like Yahner and Murdick (1991) have found value in connecting their local histories to contrast or highlight trends found in bigger-name universities.

Accumulation

Demonstrates how one source builds on the idea of another.

Although North’s (1984) essay is fundamental to many writing centers today, Lunsford (1991) takes his ideas a step further by identifying different writing center models and also expanding North’s ideas on how writing centers can help students become better writers.

Demonstrates how one source discusses the effects of another source’s ideas.

While Healy (2001) notes the concerns of having primarily email appointments in writing centers, he also notes that constraints like funding, resources, and time affect how online resources are formed. For writing centers, email is the most economical and practical option for those wanting to offer online services but cannot dedicate the time or money to other online tutoring methods. As a result, in Neaderheiser and Wolfe’s (2009) reveals that of all the online options available in higher education, over 91% of institutions utilize online tutoring through email, meaning these constraints significantly affect the types of services writing centers offer.

Discussing Specific Source Ideas/Arguments

To debate with clarity and precision, you may need to incorporate a quote into your statement. Using can help you to thoroughly introduce your quotes so that they fit in to your paragraph and your argument. Remember that you need to use the to bridge between your ideas and outside source material.

Berlin, J. (1987).  Rhetoric and reality: Writing instruction in American colleges, 1900-1985 . Carbondale: Southern Illinois University Press.

Boquet, E.H. (2001). “Our little secret”: A history of writing centers, pre- to open admissions. In R.W. Barnett & J.S. Blumner (Eds.),  The Allyn and Bacon guide to writing center theory and practice  (pp. 42-60). Boston: Allyn and Bacon.

Carino, P. (1995). Early writing centers: Toward a history.  The Writing Center Journal ,  15 (2), 103-15.

Healy, D. (2001). From place to space: Perceptual and administrative issues in the online writing center. In R.W. Barnett & J.S. Blumner (Eds.), T he Allyn and Bacon guide to writing center theory and practice  (pp. 541-554). Boston: Allyn and Bacon.

Lunsford, A. (1991). Collaboration, control, and the idea of the writing center.  The Writing Center Journal ,  12 (1), 310-75.

Neaderheiser, S. & Wolfe, J. (2009). Between technological endorsement and resistance: The state of online writing centers.  The Writing Center Journal .  29 (1), 49-75.

North, S. (1984). The idea of a writing center.  College English ,  45 (5), 433-446.

Yahner, W. & Murdick, W. (1991). The evolution of a writing center: 1972-1990.  Writing Center Journal ,  11 (2), 13-28.

Literature Syntheis 101

How To Synthesise The Existing Research (With Examples)

By: Derek Jansen (MBA) | Expert Reviewer: Eunice Rautenbach (DTech) | August 2023

One of the most common mistakes that students make when writing a literature review is that they err on the side of describing the existing literature rather than providing a critical synthesis of it. In this post, we’ll unpack what exactly synthesis means and show you how to craft a strong literature synthesis using practical examples.

This post is based on our popular online course, Literature Review Bootcamp . In the course, we walk you through the full process of developing a literature review, step by step. If it’s your first time writing a literature review, you definitely want to use this link to get 50% off the course (limited-time offer).

Overview: Literature Synthesis

• What exactly does “synthesis” mean?
• Aspect 1: Agreement
• Aspect 2: Disagreement
• Aspect 3: Key theories
• Aspect 4: Contexts
• Aspect 5: Methodologies
• Bringing it all together

What does “synthesis” actually mean?

As a starting point, let’s quickly define what exactly we mean when we use the term “synthesis” within the context of a literature review.

Simply put, literature synthesis means going beyond just describing what everyone has said and found. Instead, synthesis is about bringing together all the information from various sources to present a cohesive assessment of the current state of knowledge in relation to your study’s research aims and questions .

Put another way, a good synthesis tells the reader exactly where the current research is “at” in terms of the topic you’re interested in – specifically, what’s known , what’s not , and where there’s a need for more research .

So, how do you go about doing this?

Well, there’s no “one right way” when it comes to literature synthesis, but we’ve found that it’s particularly useful to ask yourself five key questions when you’re working on your literature review. Having done so,  you can then address them more articulately within your actual write up. So, let’s take a look at each of these questions.

1. Points Of Agreement

The first question that you need to ask yourself is: “Overall, what things seem to be agreed upon by the vast majority of the literature?”

For example, if your research aim is to identify which factors contribute toward job satisfaction, you’ll need to identify which factors are broadly agreed upon and “settled” within the literature. Naturally, there may at times be some lone contrarian that has a radical viewpoint , but, provided that the vast majority of researchers are in agreement, you can put these random outliers to the side. That is, of course, unless your research aims to explore a contrarian viewpoint and there’s a clear justification for doing so. 

Identifying what’s broadly agreed upon is an essential starting point for synthesising the literature, because you generally don’t want (or need) to reinvent the wheel or run down a road investigating something that is already well established . So, addressing this question first lays a foundation of “settled” knowledge.

Need a helping hand?

2. Points Of Disagreement

Related to the previous point, but on the other end of the spectrum, is the equally important question: “Where do the disagreements lie?” .

In other words, which things are not well agreed upon by current researchers? It’s important to clarify here that by disagreement, we don’t mean that researchers are (necessarily) fighting over it – just that there are relatively mixed findings within the empirical research , with no firm consensus amongst researchers.

This is a really important question to address as these “disagreements” will often set the stage for the research gap(s). In other words, they provide clues regarding potential opportunities for further research, which your study can then (hopefully) contribute toward filling. If you’re not familiar with the concept of a research gap, be sure to check out our explainer video covering exactly that .

3. Key Theories

The next question you need to ask yourself is: “Which key theories seem to be coming up repeatedly?” .

Within most research spaces, you’ll find that you keep running into a handful of key theories that are referred to over and over again. Apart from identifying these theories, you’ll also need to think about how they’re connected to each other. Specifically, you need to ask yourself:

• Are they all covering the same ground or do they have different focal points  or underlying assumptions ?
• Do some of them feed into each other and if so, is there an opportunity to integrate them into a more cohesive theory?
• Do some of them pull in different directions ? If so, why might this be?
• Do all of the theories define the key concepts and variables in the same way, or is there some disconnect? If so, what’s the impact of this ?

Simply put, you’ll need to pay careful attention to the key theories in your research area, as they will need to feature within your theoretical framework , which will form a critical component within your final literature review. This will set the foundation for your entire study, so it’s essential that you be critical in this area of your literature synthesis.

If this sounds a bit fluffy, don’t worry. We deep dive into the theoretical framework (as well as the conceptual framework) and look at practical examples in Literature Review Bootcamp . If you’d like to learn more, take advantage of our limited-time offer to get 60% off the standard price.

4. Contexts

The next question that you need to address in your literature synthesis is an important one, and that is: “Which contexts have (and have not) been covered by the existing research?” .

For example, sticking with our earlier hypothetical topic (factors that impact job satisfaction), you may find that most of the research has focused on white-collar , management-level staff within a primarily Western context, but little has been done on blue-collar workers in an Eastern context. Given the significant socio-cultural differences between these two groups, this is an important observation, as it could present a contextual research gap .

In practical terms, this means that you’ll need to carefully assess the context of each piece of literature that you’re engaging with, especially the empirical research (i.e., studies that have collected and analysed real-world data). Ideally, you should keep notes regarding the context of each study in some sort of catalogue or sheet, so that you can easily make sense of this before you start the writing phase. If you’d like, our free literature catalogue worksheet is a great tool for this task.

5. Methodological Approaches

Last but certainly not least, you need to ask yourself the question: “What types of research methodologies have (and haven’t) been used?”

For example, you might find that most studies have approached the topic using qualitative methods such as interviews and thematic analysis. Alternatively, you might find that most studies have used quantitative methods such as online surveys and statistical analysis.

But why does this matter?

Well, it can run in one of two potential directions . If you find that the vast majority of studies use a specific methodological approach, this could provide you with a firm foundation on which to base your own study’s methodology . In other words, you can use the methodologies of similar studies to inform (and justify) your own study’s research design .

On the other hand, you might argue that the lack of diverse methodological approaches presents a research gap , and therefore your study could contribute toward filling that gap by taking a different approach. For example, taking a qualitative approach to a research area that is typically approached quantitatively. Of course, if you’re going to go against the methodological grain, you’ll need to provide a strong justification for why your proposed approach makes sense. Nevertheless, it is something worth at least considering.

Regardless of which route you opt for, you need to pay careful attention to the methodologies used in the relevant studies and provide at least some discussion about this in your write-up. Again, it’s useful to keep track of this on some sort of spreadsheet or catalogue as you digest each article, so consider grabbing a copy of our free literature catalogue if you don’t have anything in place.

Bringing It All Together

Alright, so we’ve looked at five important questions that you need to ask (and answer) to help you develop a strong synthesis within your literature review.  To recap, these are:

• Which things are broadly agreed upon within the current research?
• Which things are the subject of disagreement (or at least, present mixed findings)?
• Which theories seem to be central to your research topic and how do they relate or compare to each other?
• Which contexts have (and haven’t) been covered?
• Which methodological approaches are most common?

Importantly, you’re not just asking yourself these questions for the sake of asking them – they’re not just a reflection exercise. You need to weave your answers to them into your actual literature review when you write it up. How exactly you do this will vary from project to project depending on the structure you opt for, but you’ll still need to address them within your literature review, whichever route you go.

The best approach is to spend some time actually writing out your answers to these questions, as opposed to just thinking about them in your head. Putting your thoughts onto paper really helps you flesh out your thinking . As you do this, don’t just write down the answers – instead, think about what they mean in terms of the research gap you’ll present , as well as the methodological approach you’ll take . Your literature synthesis needs to lay the groundwork for these two things, so it’s essential that you link all of it together in your mind, and of course, on paper.

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

You Might Also Like:

excellent , thank you

Submit a Comment Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

• Print Friendly

Table of Contents

Ai, ethics & human agency, collaboration, information literacy, writing process, synthesizing your research findings.

• CC BY-NC-ND 4.0 by Christine Photinos - National University, San Diego

Synthesis is something you already do in your everyday life.  For example, if you are shopping for a new car, the research question you are trying to answer is, “Which car should I buy”?  You explore available models, prices, options, and consumer reviews, and you make comparisons.  For example:  Car X costs more than car Y but gets better mileage.  Or:  Reviewers A, B, and C all prefer Car X, but their praise is based primarily on design features that aren’t important to you.  It is this analysis across sources that moves you towards an answer to your question.

Early in an academic research project you are likely to find yourself making initial comparisons—for example, you may notice that Source A arrives at a conclusion very different from that of Source B—but the task of synthesis will become central to your work when you begin drafting your research paper or presentation. 

Remember, when you synthesize, you are not just compiling information.  You are organizing that information around a specific argument or question, and this work—your own intellectual work—is central to research writing.

Below are some questions that highlight ways in which the act of synthesizing brings together ideas and generates new knowledge. 

How do the sources speak to your specific argument or research question?

Your argument or research question is the main unifying element in your project.  Keep this in the forefront of your mind when you write about your sources.  Explain how, specifically, each source supports your central claim/s or suggests possible answers to your question.  For example:  Does the source provide essential background information or a definitional foundation for your argument or inquiry? Does it present numerical data that supports one of your points or helps you answer a question you have posed?  Does it present a theory that might be applied to some aspect of your project?  Does it present a recognized expert’s insights on your topic? 

How do the sources speak to each other? 

Sometimes you will find explicit dialogue between sources (for example, Source A refutes Source B by name), and sometimes you will need to bring your sources into dialogue (for example, Source A does not mention Source B, but you observe that the two are advancing similar or dissimilar arguments).  Attending to interrelationships among sources is at the heart of the task of synthesis.

Begin by asking:  What are the points of agreement?  Where are there disagreements?

But be aware that you are unlikely to find your sources in pure positions of “for” vs. “against.”  You are more likely to find agreement in some areas and disagreement in other areas.  You may also find agreement but for different reasons—such as different underlying values and priorities, or different methods of inquiry.

(See also Identifying a Conversation )

Where are there, or aren’t there, information gaps?

Where is the available information unreliable (for example, it might be difficult to trace back to primary sources), or limited, (for example, based on just a few case studies, or on just one geographical area), or difficult for non-specialists to access (for example, written in specialist language, or tucked away in a physical archive)? 

Does your inquiry contain sub-questions that may not at present be answerable, or that may not be answerable without additional primary research—for example, laboratory studies, direct observation, interviews with witnesses or participants, etc.?

Or, alternatively, is there a great deal of reliable, accessible information that addresses your question or speaks to your argument or inquiry? 

In considering these questions, you are engaged in synthesis: you are conducting an overview assessment of the field of available information and in this way generating composite knowledge.

Remember, synthesis is about pulling together information from a range of sources in order to answer a question or construct an argument. It is something you will be called upon to do in a wide variety of academic, professional, and personal contexts. Being able to dive into an ocean of information and surface with meaningful conclusions is an essential life skill.

Brevity – Say More with Less

Clarity (in Speech and Writing)

Coherence – How to Achieve Coherence in Writing

Flow – How to Create Flow in Writing

Inclusivity – Inclusive Language

The Elements of Style – The DNA of Powerful Writing

Suggested Edits

• Please select the purpose of your message. * - Corrections, Typos, or Edits Technical Support/Problems using the site Advertising with Writing Commons Copyright Issues I am contacting you about something else
• Your full name
• Your email address *
• Page URL needing edits *
• Phone This field is for validation purposes and should be left unchanged.

Featured Articles

Academic Writing – How to Write for the Academic Community

Professional Writing – How to Write for the Professional World

Authority – How to Establish Credibility in Speech & Writing

• University of Oregon Libraries
• Research Guides

How to Write a Literature Review

• 6. Synthesize
• Literature Reviews: A Recap
• Reading Journal Articles
• Does it Describe a Literature Review?
• 1. Identify the Question
• 2. Review Discipline Styles
• Searching Article Databases
• Finding Full-Text of an Article
• Citation Chaining
• When to Stop Searching
• 4. Manage Your References
• 5. Critically Analyze and Evaluate

Synthesis Visualization

Synthesis matrix example.

• 7. Write a Literature Review

• Synthesis Worksheet

About Synthesis

Approaches to synthesis.

You can sort the literature in various ways, for example:

How to Begin?

Read your sources carefully and find the main idea(s) of each source

Look for similarities in your sources – which sources are talking about the same main ideas? (for example, sources that discuss the historical background on your topic)

Use the worksheet (above) or synthesis matrix (below) to get organized

This work can be messy. Don't worry if you have to go through a few iterations of the worksheet or matrix as you work on your lit review!

Four Examples of Student Writing

In the four examples below, only ONE shows a good example of synthesis: the fourth column, or  Student D . For a web accessible version, click the link below the image.

Long description of "Four Examples of Student Writing" for web accessibility

• Download a copy of the "Four Examples of Student Writing" chart

Click on the example to view the pdf.

From Jennifer Lim

• << Previous: 5. Critically Analyze and Evaluate
• Next: 7. Write a Literature Review >>
• Last Updated: Jan 10, 2024 4:46 PM
• URL: https://researchguides.uoregon.edu/litreview

Contact Us Library Accessibility UO Libraries Privacy Notices and Procedures

1501 Kincaid Street Eugene, OR 97403 P: 541-346-3053 F: 541-346-3485

• Visit us on Facebook
• Visit us on Twitter
• Visit us on Youtube
• Visit us on Instagram
• Report a Concern
• Nondiscrimination and Title IX
• Accessibility
• Privacy Policy
• Find People

• Walden University
• Faculty Portal

Using Evidence: Synthesis

Synthesis video playlist.

Note that these videos were created while APA 6 was the style guide edition in use. There may be some examples of writing that have not been updated to APA 7 guidelines.

Basics of Synthesis

As you incorporate published writing into your own writing, you should aim for synthesis of the material.

Synthesizing requires critical reading and thinking in order to compare different material, highlighting similarities, differences, and connections. When writers synthesize successfully, they present new ideas based on interpretations of other evidence or arguments. You can also think of synthesis as an extension of—or a more complicated form of—analysis. One main difference is that synthesis involves multiple sources, while analysis often focuses on one source.

Conceptually, it can be helpful to think about synthesis existing at both the local (or paragraph) level and the global (or paper) level.

Local Synthesis

Local synthesis occurs at the paragraph level when writers connect individual pieces of evidence from multiple sources to support a paragraph’s main idea and advance a paper’s thesis statement. A common example in academic writing is a scholarly paragraph that includes a main idea, evidence from multiple sources, and analysis of those multiple sources together.

Global Synthesis

Global synthesis occurs at the paper (or, sometimes, section) level when writers connect ideas across paragraphs or sections to create a new narrative whole. A literature review , which can either stand alone or be a section/chapter within a capstone, is a common example of a place where global synthesis is necessary. However, in almost all academic writing, global synthesis is created by and sometimes referred to as good cohesion and flow.

Synthesis in Literature Reviews

While any types of scholarly writing can include synthesis, it is most often discussed in the context of literature reviews. Visit our literature review pages for more information about synthesis in literature reviews.

Related Webinars

Didn't find what you need? Email us at [email protected] .

• Previous Page: Analysis
• Next Page: Citing Sources Properly
• Office of Student Disability Services

Walden Resources

Departments.

• Academic Residencies
• Academic Skills
• Career Planning and Development
• Customer Care Team
• Field Experience
• Military Services
• Student Success Advising
• Writing Skills

Centers and Offices

• Center for Social Change
• Office of Academic Support and Instructional Services
• Office of Degree Acceleration
• Office of Research and Doctoral Services
• Office of Student Affairs

Student Resources

• Doctoral Writing Assessment
• Form & Style Review
• Quick Answers
• ScholarWorks
• SKIL Courses and Workshops
• Walden Bookstore
• Walden Catalog & Student Handbook
• Student Safety/Title IX
• Legal & Consumer Information
• Website Terms and Conditions
• Cookie Policy
• Accessibility
• Accreditation
• State Authorization
• Net Price Calculator
• Contact Walden

Walden University is a member of Adtalem Global Education, Inc. www.adtalem.com Walden University is certified to operate by SCHEV © 2024 Walden University LLC. All rights reserved.

• University of Texas Libraries
• UT Libraries

Systematic Reviews & Evidence Synthesis Methods

• Types of Reviews
• Formulate Question
• Find Existing Reviews & Protocols
• Register a Protocol
• Searching Systematically
• Supplementary Searching
• Managing Results
• Deduplication
• Critical Appraisal
• Glossary of terms
• Librarian Support
• Video tutorials This link opens in a new window
• Systematic Review & Evidence Synthesis Boot Camp

Once you have completed your analysis, you will want to both summarize and synthesize those results. You may have a qualitative synthesis, a quantitative synthesis, or both.

Qualitative Synthesis

In a qualitative synthesis, you describe for readers how the pieces of your work fit together. You will summarize, compare, and contrast the characteristics and findings, exploring the relationships between them. Further, you will discuss the relevance and applicability of the evidence to your research question. You will also analyze the strengths and weaknesses of the body of evidence. Focus on where the gaps are in the evidence and provide recommendations for further research.

Quantitative Synthesis

Whether or not your Systematic Review includes a full meta-analysis, there is typically some element of data analysis. The quantitative synthesis combines and analyzes the evidence using statistical techniques. This includes comparing methodological similarities and differences and potentially the quality of the studies conducted.

Summarizing vs. Synthesizing

In a systematic review, researchers do more than summarize findings from identified articles. You will synthesize the information you want to include.

While a summary is a way of concisely relating important themes and elements from a larger work or works in a condensed form, a synthesis takes the information from a variety of works and combines them together to create something new.

Synthesis :

"The goal of a systematic synthesis of qualitative research is to integrate or compare the results across studies in order to increase understanding of a particular phenomenon, not to add studies together. Typically the aim is to identify broader themes or new theories – qualitative syntheses usually result in a narrative summary of cross-cutting or emerging themes or constructs, and/or conceptual models."

Denner, J., Marsh, E. & Campe, S. (2017). Approaches to reviewing research in education. In D. Wyse, N. Selwyn, & E. Smith (Eds.), The BERA/SAGE Handbook of educational research (Vol. 2, pp. 143-164). doi: 10.4135/9781473983953.n7

• Approaches to Reviewing Research in Education from Sage Knowledge

Data synthesis  (Collaboration for Environmental Evidence Guidebook)

Interpreting findings and and reporting conduct   (Collaboration for Environmental Evidence Guidebook)

Interpreting results and drawing conclusions  (Cochrane Handbook, Chapter 15)

Guidance on the conduct of narrative synthesis in systematic reviews  (ESRC Methods Programme)

• Last Updated: Apr 9, 2024 8:57 PM
• URL: https://guides.lib.utexas.edu/systematicreviews

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• BMC Med Res Methodol

Methods for the synthesis of qualitative research: a critical review

Elaine barnett-page.

1 Evidence for Policy and Practice Information and Co-ordinating (EPPI-) Centre, Social Science Research Unit, 18 Woburn Square, London WC1H 0NS, UK

James Thomas

Associated data.

In recent years, a growing number of methods for synthesising qualitative research have emerged, particularly in relation to health-related research. There is a need for both researchers and commissioners to be able to distinguish between these methods and to select which method is the most appropriate to their situation.

A number of methodological and conceptual links between these methods were identified and explored, while contrasting epistemological positions explained differences in approaches to issues such as quality assessment and extent of iteration. Methods broadly fall into 'realist' or 'idealist' epistemologies, which partly accounts for these differences.

Methods for qualitative synthesis vary across a range of dimensions. Commissioners of qualitative syntheses might wish to consider the kind of product they want and select their method – or type of method – accordingly.

The range of different methods for synthesising qualitative research has been growing over recent years [ 1 , 2 ], alongside an increasing interest in qualitative synthesis to inform health-related policy and practice [ 3 ]. While the terms 'meta-analysis' (a statistical method to combine the results of primary studies), or sometimes 'narrative synthesis', are frequently used to describe how quantitative research is synthesised, far more terms are used to describe the synthesis of qualitative research. This profusion of terms can mask some of the basic similarities in approach that the different methods share, and also lead to some confusion regarding which method is most appropriate in a given situation. This paper does not argue that the various nomenclatures are unnecessary, but rather seeks to draw together and review the full range of methods of synthesis available to assist future reviewers in selecting a method that is fit for their purpose. It also represents an attempt to guide the reader through some of the varied terminology to spring up around qualitative synthesis. Other helpful reviews of synthesis methods have been undertaken in recent years with slightly different foci to this paper. Two recent studies have focused on describing and critiquing methods for the integration of qualitative research with quantitative [ 4 , 5 ] rather than exclusively examining the detail and rationale of methods for the synthesis of qualitative research. Two other significant pieces of work give practical advice for conducting the synthesis of qualitative research, but do not discuss the full range of methods available [ 6 , 7 ]. We begin our Discussion by outlining each method of synthesis in turn, before comparing and contrasting characteristics of these different methods across a range of dimensions. Readers who are more familiar with the synthesis methods described here may prefer to turn straight to the 'dimensions of difference' analysis in the second part of the Discussion.

Overview of synthesis methods

Meta-ethnography.

In their seminal work of 1988, Noblit and Hare proposed meta-ethnography as an alternative to meta-analysis [ 8 ]. They cited Strike and Posner's [ 9 ] definition of synthesis as an activity in which separate parts are brought together to form a 'whole'; this construction of the whole is essentially characterised by some degree of innovation, so that the result is greater than the sum of its parts. They also borrowed from Turner's theory of social explanation [ 10 ], a key tenet of which was building 'comparative understanding' [[ 8 ], p22] rather than aggregating data.

To Noblit and Hare, synthesis provided an answer to the question of 'how to "put together" written interpretive accounts' [[ 8 ], p7], where mere integration would not be appropriate. Noblit and Hare's early work synthesised research from the field of education.

Three different methods of synthesis are used in meta-ethnography. One involves the 'translation' of concepts from individual studies into one another, thereby evolving overarching concepts or metaphors. Noblit and Hare called this process reciprocal translational analysis (RTA). Refutational synthesis involves exploring and explaining contradictions between individual studies. Lines-of-argument (LOA) synthesis involves building up a picture of the whole (i.e. culture, organisation etc) from studies of its parts. The authors conceptualised this latter approach as a type of grounded theorising.

Britten et al [ 11 ] and Campbell et al [ 12 ] have both conducted evaluations of meta-ethnography and claim to have succeeded, by using this method, in producing theories with greater explanatory power than could be achieved in a narrative literature review. While both these evaluations used small numbers of studies, more recently Pound et al [ 13 ] conducted both an RTA and an LOA synthesis using a much larger number of studies (37) on resisting medicines. These studies demonstrate that meta-ethnography has evolved since Noblit and Hare first introduced it. Campbell et al claim to have applied the method successfully to non-ethnographical studies. Based on their reading of Schutz [ 14 ], Britten et al have developed both second and third order constructs in their synthesis (Noblit and Hare briefly allude to the possibility of a 'second level of synthesis' [[ 8 ], p28] but do not demonstrate or further develop the idea).

In a more recent development, Sandelowski & Barroso [ 15 ] write of adapting RTA by using it to ' integrate findings interpretively, as opposed to comparing them interpretively' (p204). The former would involve looking to see whether the same concept, theory etc exists in different studies; the latter would involve the construction of a bigger picture or theory (i.e. LOA synthesis). They also talk about comparing or integrating imported concepts (e.g. from other disciplines) as well as those evolved 'in vivo'.

Grounded theory

Kearney [ 16 ], Eaves [ 17 ] and Finfgeld [ 18 ] have all adapted grounded theory to formulate a method of synthesis. Key methods and assumptions of grounded theory, as originally formulated and subsequently refined by Glaser and Strauss [ 19 ] and Strauss and Corbin [ 20 , 21 ], include: simultaneous phases of data collection and analysis; an inductive approach to analysis, allowing the theory to emerge from the data; the use of the constant comparison method; the use of theoretical sampling to reach theoretical saturation; and the generation of new theory. Eaves cited grounded theorists Charmaz [ 22 ] and Chesler [ 23 ], as well as Strauss and Corbin [ 20 ], as informing her approach to synthesis.

Glaser and Strauss [ 19 ] foresaw a time when a substantive body of grounded research should be pushed towards a higher, more abstract level. As a piece of methodological work, Eaves undertook her own synthesis of the synthesis methods used by these authors to produce her own clear and explicit guide to synthesis in grounded formal theory. Kearney stated that 'grounded formal theory', as she termed this method of synthesis, 'is suited to study of phenomena involving processes of contextualized understanding and action' [[ 24 ], p180] and, as such, is particularly applicable to nurses' research interests.

As Kearney suggested, the examples examined here were largely dominated by research in nursing. Eaves synthesised studies on care-giving in rural African-American families for elderly stroke survivors; Finfgeld on courage among individuals with long-term health problems; Kearney on women's experiences of domestic violence.

Kearney explicitly chose 'grounded formal theory' because it matches 'like' with 'like': that is, it applies the same methods that have been used to generate the original grounded theories included in the synthesis – produced by constant comparison and theoretical sampling – to generate a higher-level grounded theory. The wish to match 'like' with 'like' is also implicit in Eaves' paper. This distinguishes grounded formal theory from more recent applications of meta-ethnography, which have sought to include qualitative research using diverse methodological approaches [ 12 ].

Thematic Synthesis

Thomas and Harden [ 25 ] have developed an approach to synthesis which they term 'thematic synthesis'. This combines and adapts approaches from both meta-ethnography and grounded theory. The method was developed out of a need to conduct reviews that addressed questions relating to intervention need, appropriateness and acceptability – as well as those relating to effectiveness – without compromising on key principles developed in systematic reviews. They applied thematic synthesis in a review of the barriers to, and facilitators of, healthy eating amongst children.

Free codes of findings are organised into 'descriptive' themes, which are then further interpreted to yield 'analytical' themes. This approach shares characteristics with later adaptations of meta-ethnography, in that the analytical themes are comparable to 'third order interpretations' and that the development of descriptive and analytical themes using coding invoke reciprocal 'translation'. It also shares much with grounded theory, in that the approach is inductive and themes are developed using a 'constant comparison' method. A novel aspect of their approach is the use of computer software to code the results of included studies line-by-line, thus borrowing another technique from methods usually used to analyse primary research.

Textual Narrative Synthesis

Textual narrative synthesis is an approach which arranges studies into more homogenous groups. Lucas et al [ 26 ] comment that it has proved useful in synthesising evidence of different types (qualitative, quantitative, economic etc). Typically, study characteristics, context, quality and findings are reported on according to a standard format and similarities and differences are compared across studies. Structured summaries may also be developed, elaborating on and putting into context the extracted data [ 27 ].

Lucas et al [ 26 ] compared thematic synthesis with textual narrative synthesis. They found that 'thematic synthesis holds most potential for hypothesis generation' whereas textual narrative synthesis is more likely to make transparent heterogeneity between studies (as does meta-ethnography, with refutational synthesis) and issues of quality appraisal. This is possibly because textual narrative synthesis makes clearer the context and characteristics of each study, while the thematic approach organises data according to themes. However, Lucas et al found that textual narrative synthesis is 'less good at identifying commonality' (p2); the authors do not make explicit why this should be, although it may be that organising according to themes, as the thematic approach does, is comparatively more successful in revealing commonality.

Paterson et al [ 28 ] have evolved a multi-faceted approach to synthesis, which they call 'meta-study'. The sociologist Zhao [ 29 ], drawing on Ritzer's work [ 30 ], outlined three components of analysis, which they proposed should be undertaken prior to synthesis. These are meta-data-analysis (the analysis of findings), meta-method (the analysis of methods) and meta-theory (the analysis of theory). Collectively, these three elements of analysis, culminating in synthesis, make up the practice of 'meta-study'. Paterson et al pointed out that the different components of analysis may be conducted concurrently.

Paterson et al argued that primary research is a construction; secondary research is therefore a construction of a construction. There is need for an approach that recognises this, and that also recognises research to be a product of its social, historical and ideological context. Such an approach would be useful in accounting for differences in research findings. For Paterson et al, there is no such thing as 'absolute truth'.

Meta-study was developed to study the experiences of adults living with a chronic illness. Meta-data-analysis was conceived of by Paterson et al in similar terms to Noblit and Hare's meta-ethnography (see above), in that it is essentially interpretive and seeks to reveal similarities and discrepancies among accounts of a particular phenomenon. Meta-method involves the examination of the methodologies of the individual studies under review. Part of the process of meta-method is to consider different aspects of methodology such as sampling, data collection, research design etc, similar to procedures others have called 'critical appraisal' (CASP [ 31 ]). However, Paterson et al take their critique to a deeper level by establishing the underlying assumptions of the methodologies used and the relationship between research outcomes and methods used. Meta-theory involves scrutiny of the philosophical and theoretical assumptions of the included research papers; this includes looking at the wider context in which new theory is generated. Paterson et al described meta-synthesis as a process which creates a new interpretation which accounts for the results of all three elements of analysis. The process of synthesis is iterative and reflexive and the authors were unwilling to oversimplify the process by 'codifying' procedures for bringing all three components of analysis together.

Meta-narrative

Greenhalgh et al [ 32 ]'s meta-narrative approach to synthesis arose out of the need to synthesise evidence to inform complex policy-making questions and was assisted by the formation of a multi-disciplinary team. Their approach to review was informed by Thomas Kuhn's The Structure of Scientific Revolutions [ 33 ], in which he proposed that knowledge is produced within particular paradigms which have their own assumptions about theory, about what is a legitimate object of study, about what are legitimate research questions and about what constitutes a finding. Paradigms also tend to develop through time according to a particular set of stages, central to which is the stage of 'normal science', in which the particular standards of the paradigm are largely unchallenged and seen to be self-evident. As Greenhalgh et al pointed out, Kuhn saw paradigms as largely incommensurable: 'that is, an empirical discovery made using one set of concepts, theories, methods and instruments cannot be satisfactorily explained through a different paradigmatic lens' [[ 32 ], p419].

Greenhalgh et al synthesised research from a wide range of disciplines; their research question related to the diffusion of innovations in health service delivery and organisation. They thus identified a need to synthesise findings from research which contains many different theories arising from many different disciplines and study designs.

Based on Kuhn's work, Greenhalgh et al proposed that, across different paradigms, there were multiple – and potentially mutually contradictory – ways of understanding the concept at the heart of their review, namely the diffusion of innovation. Bearing this in mind, the reviewers deliberately chose to select key papers from a number of different research 'paradigms' or 'traditions', both within and beyond healthcare, guided by their multidisciplinary research team. They took as their unit of analysis the 'unfolding "storyline" of a research tradition over time' [[ 32 ], p417) and sought to understand diffusion of innovation as it was conceptualised in each of these traditions. Key features of each tradition were mapped: historical roots, scope, theoretical basis; research questions asked and methods/instruments used; main empirical findings; historical development of the body of knowledge (how have earlier findings led to later findings); and strengths and limitations of the tradition. The results of this exercise led to maps of 13 'meta-narratives' in total, from which seven key dimensions, or themes, were identified and distilled for the synthesis phase of the review.

Critical Interpretive Synthesis

Dixon-Woods et al [ 34 ] developed their own approach to synthesising multi-disciplinary and multi-method evidence, termed 'critical interpretive synthesis', while researching access to healthcare by vulnerable groups. Critical interpretive synthesis is an adaptation of meta-ethnography, as well as borrowing techniques from grounded theory. The authors stated that they needed to adapt traditional meta-ethnographic methods for synthesis, since these had never been applied to quantitative as well as qualitative data, nor had they been applied to a substantial body of data (in this case, 119 papers).

Dixon-Woods et al presented critical interpretive synthesis as an approach to the whole process of review, rather than to just the synthesis component. It involves an iterative approach to refining the research question and searching and selecting from the literature (using theoretical sampling) and defining and applying codes and categories. It also has a particular approach to appraising quality, using relevance – i.e. likely contribution to theory development – rather than methodological characteristics as a means of determining the 'quality' of individual papers [ 35 ]. The authors also stress, as a defining characteristic, critical interpretive synthesis's critical approach to the literature in terms of deconstructing research traditions or theoretical assumptions as a means of contextualising findings.

Dixon-Woods et al rejected reciprocal translational analysis (RTA) as this produced 'only a summary in terms that have already been used in the literature' [[ 34 ], p5], which was seen as less helpful when dealing with a large and diverse body of literature. Instead, Dixon-Woods et al adopted a lines-of-argument (LOA) synthesis, in which – rejecting the difference between first, second and third order constructs – they instead developed 'synthetic constructs' which were then linked with constructs arising directly from the literature.

The influence of grounded theory can be seen in particular in critical interpretive synthesis's inductive approach to formulating the review question and to developing categories and concepts, rejecting a 'stage' approach to systematic reviewing, and in selecting papers using theoretical sampling. Dixon-Woods et al also claim that critical interpretive synthesis is distinct in its 'explicit orientation towards theory generation' [[ 34 ], p9].

Ecological Triangulation

Jim Banning is the author of 'ecological triangulation' or 'ecological sentence synthesis', applying this method to the evidence for what works for youth with disabilities. He borrows from Webb et al [ 36 ] and Denzin [ 37 ] the concept of triangulation, in which phenomena are studied from a variety of vantage points. His rationale is that building an 'evidence base' of effectiveness requires the synthesis of cumulative, multi-faceted evidence in order to find out 'what intervention works for what kind of outcomes for what kind of persons under what kind of conditions' [[ 38 ], p1].

Ecological triangulation unpicks the mutually interdependent relationships between behaviour, persons and environments. The method requires that, for data extraction and synthesis, 'ecological sentences' are formulated following the pattern: 'With this intervention, these outcomes occur with these population foci and within these grades (ages), with these genders ... and these ethnicities in these settings' [[ 39 ], p1].

Framework Synthesis

Brunton et al [ 40 ] and Oliver et al [ 41 ] have applied a 'framework synthesis' approach in their reviews. Framework synthesis is based on framework analysis, which was outlined by Pope, Ziebland and Mays [ 42 ], and draws upon the work of Ritchie and Spencer [ 43 ] and Miles and Huberman [ 44 ]. Its rationale is that qualitative research produces large amounts of textual data in the form of transcripts, observational fieldnotes etc. The sheer wealth of information poses a challenge for rigorous analysis. Framework synthesis offers a highly structured approach to organising and analysing data (e.g. indexing using numerical codes, rearranging data into charts etc).

Brunton et al applied the approach to a review of children's, young people's and parents' views of walking and cycling; Oliver et al to an analysis of public involvement in health services research. Framework synthesis is distinct from the other methods outlined here in that it utilises an a priori 'framework' – informed by background material and team discussions – to extract and synthesise findings. As such, it is largely a deductive approach although, in addition to topics identified by the framework, new topics may be developed and incorporated as they emerge from the data. The synthetic product can be expressed in the form of a chart for each key dimension identified, which may be used to map the nature and range of the concept under study and find associations between themes and exceptions to these [ 40 ].

'Fledgling' approaches

There are three other approaches to synthesis which have not yet been widely used. One is an approach using content analysis [ 45 , 46 ] in which text is condensed into fewer content-related categories. Another is 'meta-interpretation' [ 47 ], featuring the following: an ideographic rather than pre-determined approach to the development of exclusion criteria; a focus on meaning in context; interpretations as raw data for synthesis (although this feature doesn't distinguish it from other synthesis methods); an iterative approach to the theoretical sampling of studies for synthesis; and a transparent audit trail demonstrating the trustworthiness of the synthesis.

In addition to the synthesis methods discussed above, Sandelowski and Barroso propose a method they call 'qualitative metasummary' [ 15 ]. It is mentioned here as a new and original approach to handling a collection of qualitative studies but is qualitatively different to the other methods described here since it is aggregative; that is, findings are accumulated and summarised rather than 'transformed'. Metasummary is a way of producing a 'map' of the contents of qualitative studies and – according to Sandelowski and Barroso – 'reflect [s] a quantitative logic' [[ 15 ], p151]. The frequency of each finding is determined and the higher the frequency of a particular finding, the greater its validity. The authors even discuss the calculation of 'effect sizes' for qualitative findings. Qualitative metasummaries can be undertaken as an end in themselves or may serve as a basis for a further synthesis.

Dimensions of difference

Having outlined the range of methods identified, we now turn to an examination of how they compare with one another. It is clear that they have come from many different contexts and have different approaches to understanding knowledge, but what do these differences mean in practice? Our framework for this analysis is shown in Additional file 1 : dimensions of difference [ 48 ]. We have examined the epistemology of each of the methods and found that, to some extent, this explains the need for different methods and their various approaches to synthesis.

Epistemology

The first dimension that we will consider is that of the researchers' epistemological assumptions. Spencer et al [ 49 ] outline a range of epistemological positions, which might be organised into a spectrum as follows:

Subjective idealism : there is no shared reality independent of multiple alternative human constructions

Objective idealism : there is a world of collectively shared understandings

Critical realism : knowledge of reality is mediated by our perceptions and beliefs

Scientific realism : it is possible for knowledge to approximate closely an external reality

Naïve realism : reality exists independently of human constructions and can be known directly [ 49 , 45 , 46 ].

Thus, at one end of the spectrum we have a highly constructivist view of knowledge and, at the other, an unproblematized 'direct window onto the world' view.

Nearly all of positions along this spectrum are represented in the range of methodological approaches to synthesis covered in this paper. The originators of meta-narrative synthesis, critical interpretive synthesis and meta-study all articulate what might be termed a 'subjective idealist' approach to knowledge. Paterson et al [ 28 ] state that meta-study shies away from creating 'grand theories' within the health or social sciences and assume that no single objective reality will be found. Primary studies, they argue, are themselves constructions; meta-synthesis, then, 'deals with constructions of constructions' (p7). Greenhalgh et al [ 32 ] also view knowledge as a product of its disciplinary paradigm and use this to explain conflicting findings: again, the authors neither seek, nor expect to find, one final, non-contestable answer to their research question. Critical interpretive synthesis is similar in seeking to place literature within its context, to question its assumptions and to produce a theoretical model of a phenomenon which – because highly interpretive – may not be reproducible by different research teams at alternative points in time [[ 34 ], p11].

Methods used to synthesise grounded theory studies in order to produce a higher level of grounded theory [ 24 ] appear to be informed by 'objective idealism', as does meta-ethnography. Kearney argues for the near-universal applicability of a 'ready-to-wear' theory across contexts and populations. This approach is clearly distinct from one which recognises multiple realities. The emphasis is on examining commonalities amongst, rather than discrepancies between, accounts. This emphasis is similarly apparent in most meta-ethnographies, which are conducted either according to Noblit and Hare's 'reciprocal translational analysis' technique or to their 'lines-of-argument' technique and which seek to provide a 'whole' which has a greater explanatory power. Although Noblit and Hare also propose 'refutational synthesis', in which contradictory findings might be explored, there are few examples of this having been undertaken in practice, and the aim of the method appears to be to explain and explore differences due to context, rather than multiple realities.

Despite an assumption of a reality which is perhaps less contestable than those of meta-narrative synthesis, critical interpretive synthesis and meta-study, both grounded formal theory and meta-ethnography place a great deal of emphasis on the interpretive nature of their methods. This still supposes a degree of constructivism. Although less explicit about how their methods are informed, it seems that both thematic synthesis and framework synthesis – while also involving some interpretation of data – share an even less problematized view of reality and a greater assumption that their synthetic products are reproducible and correspond to a shared reality. This is also implicit in the fact that such products are designed directly to inform policy and practice, a characteristic shared by ecological triangulation. Notably, ecological triangulation, according to Banning, can be either realist or idealist. Banning argues that the interpretation of triangulation can either be one in which multiple viewpoints converge on a point to produce confirming evidence (i.e. one definitive answer to the research question) or an idealist one, in which the complexity of multiple viewpoints is represented. Thus, although ecological triangulation views reality as complex, the approach assumes that it can be approximately knowable (at least when the realist view of ecological triangulation is adopted) and that interventions can and should be modelled according to the products of its syntheses.

While pigeonholing different methods into specific epistemological positions is a problematic process, we do suggest that the contrasting epistemologies of different researchers is one way of explaining why we have – and need – different methods for synthesis.

Variation in terms of the extent of iteration during the review process is another key dimension. All synthesis methods include some iteration but the degree varies. Meta-ethnography, grounded theory and thematic synthesis all include iteration at the synthesis stage; both framework synthesis and critical interpretive synthesis involve iterative literature searching – in the case of critical interpretive synthesis, it is not clear whether iteration occurs during the rest of the review process. Meta-narrative also involves iteration at every stage. Banning does not mention iteration in outlining ecological triangulation and neither do Lucas or Thomas and Harden for thematic narrative synthesis.

It seems that the more idealist the approach, the greater the extent of iteration. This might be because a large degree of iteration does not sit well with a more 'positivist' ideal of procedural objectivity; in particular, the notion that the robustness of the synthetic product depends in part on the reviewers stating up front in a protocol their searching strategies, inclusion/exclusion criteria etc, and being seen not to alter these at a later stage.

Quality assessment

Another dimension along which we can look at different synthesis methods is that of quality assessment. When the approaches to the assessment of the quality of studies retrieved for review are examined, there is again a wide methodological variation. It might be expected that the further towards the 'realism' end of the epistemological spectrum a method of synthesis falls, the greater the emphasis on quality assessment. In fact, this is only partially the case.

Framework synthesis, thematic narrative synthesis and thematic synthesis – methods which might be classified as sharing a 'critical realist' approach – all have highly specified approaches to quality assessment. The review in which framework synthesis was developed applied ten quality criteria: two on quality and reporting of sampling methods, four to the quality of the description of the sample in the study, two to the reliability and validity of the tools used to collect data and one on whether studies used appropriate methods for helping people to express their views. Studies which did not meet a certain number of quality criteria were excluded from contributing to findings. Similarly, in the example review for thematic synthesis, 12 criteria were applied: five related to reporting aims, context, rationale, methods and findings; four relating to reliability and validity; and three relating to the appropriateness of methods for ensuring that findings were rooted in participants' own perspectives. Studies which were deemed to have significant flaws were excluded and sensitivity analyses were used to assess the possible impact of study quality on the review's findings. Thomas and Harden's use of thematic narrative synthesis similarly applied quality criteria and developed criteria additional to those they found in the literature on quality assessment, relating to the extent to which people's views and perspectives had been privileged by researchers. It is worth noting not only that these methods apply quality criteria but that they are explicit about what they are: assessing quality is a key component in the review process for both of these methods. Likewise, Banning – the originator of ecological triangulation – sees quality assessment as important and adapts the Design and Implementation Assessment Device (DIAD) Version 0.3 (a quality assessment tool for quantitative research) for use when appraising qualitative studies [ 50 ]. Again, Banning writes of excluding studies deemed to be of poor quality.

Greenhalgh et al's meta-narrative review [ 32 ] modified a range of existing quality assessment tools to evaluate studies according to validity and robustness of methods; sample size and power; and validity of conclusions. The authors imply, but are not explicit, that this process formed the basis for the exclusion of some studies. Although not quite so clear about quality assessment methods as framework and thematic synthesis, it might be argued that meta-narrative synthesis shows a greater commitment to the concept that research can and should be assessed for quality than either meta-ethnography or grounded formal theory. The originators of meta-ethnography, Noblit and Hare [ 8 ], originally discussed quality in terms of quality of metaphor, while more recent use of this method has used amended versions of CASP (the Critical Appraisal Skills Programme tool, [ 31 ]), yet has only referred to studies being excluded on the basis of lack of relevance or because they weren't 'qualitative' studies [ 8 ]. In grounded theory, quality assessment is only discussed in terms of a 'personal note' being made on the context, quality and usefulness of each study. However, contrary to expectation, meta-narrative synthesis lies at the extreme end of the idealism/realism spectrum – as a subjective idealist approach – while meta-ethnography and grounded theory are classified as objective idealist approaches.

Finally, meta-study and critical interpretive synthesis – two more subjective idealist approaches – look to the content and utility of findings rather than methodology in order to establish quality. While earlier forms of meta-study included only studies which demonstrated 'epistemological soundness', in its most recent form [ 51 ] this method has sought to include all relevant studies, excluding only those deemed not to be 'qualitative' research. Critical interpretive synthesis also conforms to what we might expect of its approach to quality assessment: quality of research is judged as the extent to which it informs theory. The threshold of inclusion is informed by expertise and instinct rather than being articulated a priori.

In terms of quality assessment, it might be important to consider the academic context in which these various methods of synthesis developed. The reason why thematic synthesis, framework synthesis and ecological triangulation have such highly specified approaches to quality assessment may be that each of these was developed for a particular task, i.e. to conduct a multi-method review in which randomised controlled trials (RCTs) were included. The concept of quality assessment in relation to RCTs is much less contested and there is general agreement on criteria against which quality should be judged.

Problematizing the literature

Critical interpretive synthesis, the meta-narrative approach and the meta-theory element of meta-study all share some common ground in that their review and synthesis processes include examining all aspects of the context in which knowledge is produced. In conducting a review on access to healthcare by vulnerable groups, critical interpretive synthesis sought to question 'the ways in which the literature had constructed the problematics of access, the nature of the assumptions on which it drew, and what has influenced its choice of proposed solutions' [[ 34 ], p6]. Although not claiming to have been directly influenced by Greenhalgh et al's meta-narrative approach, Dixon-Woods et al do cite it as sharing similar characteristics in the sense that it critiques the literature it reviews.

Meta-study uses meta-theory to describe and deconstruct the theories that shape a body of research and to assess its quality. One aspect of this process is to examine the historical evolution of each theory and to put it in its socio-political context, which invites direct comparison with meta-narrative synthesis. Greenhalgh et al put a similar emphasis on placing research findings within their social and historical context, often as a means of seeking to explain heterogeneity of findings. In addition, meta-narrative shares with critical interpretive synthesis an iterative approach to searching and selecting from the literature.

Framework synthesis, thematic synthesis, textual narrative synthesis, meta-ethnography and grounded theory do not share the same approach to problematizing the literature as critical interpretive synthesis, meta-study and meta-narrative. In part, this may be explained by the extent to which studies included in the synthesis represented a broad range of approaches or methodologies. This, in turn, may reflect the broadness of the review question and the extent to which the concepts contained within the question are pre-defined within the literature. In the case of both the critical interpretive synthesis and meta-narrative reviews, terminology was elastic and/or the question formed iteratively. Similarly, both reviews placed great emphasis on employing multi-disciplinary research teams. Approaches which do not critique the literature in the same way tend to have more narrowly-focused questions. They also tend to include a more limited range of studies: grounded theory synthesis includes grounded theory studies, meta-ethnography (in its original form, as applied by Noblit and Hare) ethnographies. The thematic synthesis incorporated studies based on only a narrow range of qualitative methodologies (interviews and focus groups) which were informed by a similarly narrow range of epistemological assumptions. It may be that the authors of such syntheses saw no need for including such a critique in their review process.

Similarities and differences between primary studies

Most methods of synthesis are applicable to heterogeneous data (i.e. studies which use contrasting methodologies) apart from early meta-ethnography and synthesis informed by grounded theory. All methods of synthesis state that, at some level, studies are compared; many are not so explicit about how this is done, though some are. Meta-ethnography is one of the most explicit: it describes the act of 'translation' where terms and concepts which have resonance with one another are subsumed into 'higher order constructs'. Grounded theory, as represented by Eaves [ 17 ], is undertaken according to a long list of steps and sub-steps, includes the production of generalizations about concepts/categories, which comes from classifying these categories. In meta-narrative synthesis, comparable studies are grouped together at the appraisal phase of review.

Perhaps more interesting are the ways in which differences between studies are explored. Those methods with a greater emphasis on critical appraisal may tend (although this is not always made explicit) to use differences in method to explain differences in finding. Meta-ethnography proposes 'refutational synthesis' to explain differences, although there are few examples of this in the literature. Some synthesis methods – for example, thematic synthesis – look at other characteristics of the studies under review, whether types of participants and their context vary, and whether this can explain differences in perspective.

All of these methods, then, look within the studies to explain differences. Other methods look beyond the study itself to the context in which it was produced. Critical interpretive synthesis and meta-study look at differences in theory or in socio-economic context. Critical interpretive synthesis, like meta-narrative, also explores epistemological orientation. Meta-narrative is unique in concerning itself with disciplinary paradigm (i.e. the story of the discipline as it progresses). It is also distinctive in that it treats conflicting findings as 'higher order data' [[ 32 ], p420], so that the main emphasis of the synthesis appears to be on examining and explaining contradictions in the literature.

Going 'beyond' the primary studies

Synthesis is sometimes defined as a process resulting in a product, a 'whole', which is more than the sum of its parts. However, the methods reviewed here vary in the extent to which they attempt to 'go beyond' the primary studies and transform the data. Some methods – textual narrative synthesis, ecological triangulation and framework synthesis – focus on describing and summarising their primary data (often in a highly structured and detailed way) and translating the studies into one another. Others – meta-ethnography, grounded theory, thematic synthesis, meta-study, meta-narrative and critical interpretive synthesis – seek to push beyond the original data to a fresh interpretation of the phenomena under review. A key feature of thematic synthesis is its clear differentiation between these two stages.

Different methods have different mechanisms for going beyond the primary studies, although some are more explicit than others about what these entail. Meta-ethnography proposes a 'Line of Argument' (LOA) synthesis in which an interpretation is constructed to both link and explain a set of parts. Critical interpretive synthesis based its synthesis methods on those of meta-ethnography, developing an LOA using what the authors term 'synthetic constructs' (akin to 'third order constructs' in meta-ethnography) to create a 'synthesising argument'. Dixon-Woods et al claim that this is an advance on Britten et al's methods, in that they reject the difference between first, second and third order constructs.

Meta-narrative, as outlined above, focuses on conflicting findings and constructs theories to explain these in terms of differing paradigms. Meta study derives questions from each of its three components to which it subjects the dataset and inductively generates a number of theoretical claims in relation to it. According to Eaves' model of grounded theory [ 17 ], mini-theories are integrated to produce an explanatory framework. In ecological triangulation, the 'axial' codes – or second level codes evolved from the initial deductive open codes – are used to produce Banning's 'ecological sentence' [ 39 ].

The synthetic product

In overviewing and comparing different qualitative synthesis methods, the ultimate question relates to the utility of the synthetic product: what is it for? It is clear that some methods of synthesis – namely, thematic synthesis, textual narrative synthesis, framework synthesis and ecological triangulation – view themselves as producing an output that is directly applicable to policy makers and designers of interventions. The example of framework synthesis examined here (on children's, young people's and parents' views of walking and cycling) involved policy makers and practitioners in directing the focus of the synthesis and used the themes derived from the synthesis to infer what kind of interventions might be most effective in encouraging walking and cycling. Likewise, the products of the thematic synthesis took the form of practical recommendations for interventions (e.g. 'do not promote fruit and vegetables in the same way in the same intervention'). The extent to which policy makers and practitioners are involved in informing either synthesis or recommendation is less clear from the documents published on ecological triangulation, but the aim certainly is to directly inform practice.

The outputs of synthesis methods which have a more constructivist orientation – meta-study, meta-narrative, meta-ethnography, grounded theory, critical interpretive synthesis – tend to look rather different. They are generally more complex and conceptual, sometimes operating on the symbolic or metaphorical level, and requiring a further process of interpretation by policy makers and practitioners in order for them to inform practice. This is not to say, however, that they are not useful for practice, more that they are doing different work. However, it may be that, in the absence of further interpretation, they are more useful for informing other researchers and theoreticians.

Looking across dimensions

After examining the dimensions of difference of our included methods, what picture ultimately emerges? It seems clear that, while similar in some respects, there are genuine differences in approach to the synthesis of what is essentially textual data. To some extent, these differences can be explained by the epistemological assumptions that underpin each method. Our methods split into two broad camps: the idealist and the realist (see Table ​ Table1 1 for a summary). Idealist approaches generally tend to have a more iterative approach to searching (and the review process), have less a priori quality assessment procedures and are more inclined to problematize the literature. Realist approaches are characterised by a more linear approach to searching and review, have clearer and more well-developed approaches to quality assessment, and do not problematize the literature.

Summary table

N.B.: In terms of the above dimensions, it is generally a question of degree rather than of absolute distinctions.

Mapping the relationships between methods

What is interesting is the relationship between these methods of synthesis, the conceptual links between them, and the extent to which the originators cite – or, in some cases, don't cite – one another. Some methods directly build on others – framework synthesis builds on framework analysis, for example, while grounded theory and constant comparative analysis build on grounded theory. Others further develop existing methods – meta-study, critical interpretive synthesis and meta-narrative all adapt aspects of meta-ethnography, while also importing concepts from other theorists (critical interpretive synthesis also adapts grounded theory techniques).

Some methods share a clear conceptual link, without directly citing one another: for example, the analytical themes developed during thematic synthesis are comparable to the third order interpretations of meta-ethnography. The meta-theory aspect of meta-study is echoed in both meta-narrative synthesis and critical interpretive synthesis (see 'Problematizing the literature, above); however, the originators of critical interpretive synthesis only refer to the originators of meta-study in relation to their use of sampling techniques.

While methods for qualitative synthesis have many similarities, there are clear differences in approach between them, many of which can be explained by taking account of a given method's epistemology.

However, within the two broad idealist/realist categories, any differences between methods in terms of outputs appear to be small.

Since many systematic reviews are designed to inform policy and practice, it is important to select a method – or type of method – that will produce the kind of conclusions needed. However, it is acknowledged that this is not always simple or even possible to achieve in practice.

The approaches that result in more easily translatable messages for policy-makers and practitioners may appear to be more attractive than the others; but we do need to take account lessons from the more idealist end of the spectrum, that some perspectives are not universal.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

Both authors made substantial contributions, with EBP taking a lead on writing and JT on the analytical framework. Both authors read and approved the final manuscript.

Pre-publication history

The pre-publication history for this paper can be accessed here:

http://www.biomedcentral.com/1471-2288/9/59/prepub

Supplementary Material

Dimensions of difference . Ranging from subjective idealism through objective idealism and critical realism to scientific realism to naïve realism

Acknowledgements

The authors would like to acknowledge the helpful contributions of the following in commenting on earlier drafts of this paper: David Gough, Sandy Oliver, Angela Harden, Mary Dixon-Woods, Trisha Greenhalgh and Barbara L. Paterson. We would also like to thank the peer reviewers: Helen J Smith, Rosaline Barbour and Mark Rodgers for their helpful reviews. The methodological development was supported by the Department of Health (England) and the ESRC through the Methods for Research Synthesis Node of the National Centre for Research Methods (NCRM). An earlier draft of this paper currently appears as a working paper on the National Centre for Research Methods' website http://www.ncrm.ac.uk/ .

• Dixon-Woods M, Agarwhal S, Jones D, Young B, Sutton A. Synthesising qualitative and quantitative evidence: a review of possible methods. J Health Serv Res Pol. 2005; 10 (1):45–53b. doi: 10.1258/1355819052801804. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Barbour RS, Barbour M. Evaluating and synthesizing qualitative research: the need to develop a distinctive approach. J Eval Clin Pract. 2003; 9 (2):179–186. doi: 10.1046/j.1365-2753.2003.00371.x. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Mays N, Pope C, Popay J. Systematically reviewing qualitative and quantitative evidence to inform management and policy-making in the health field. J Health Serv Res Pol. 2005; 10 (Suppl 1):6–20. doi: 10.1258/1355819054308576. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Dixon-Woods M, Bonas S, Booth A, Jones DR, Miller T, Shaw RL, Smith J, Sutton A, Young B. How can systematic reviews incorporate qualitative research? A critical perspective. Qual Res. 2006; 6 :27–44. doi: 10.1177/1468794106058867. [ CrossRef ] [ Google Scholar ]
• Pope C, Mays N, Popay J. Synthesizing Qualitative and Quantitative Health Evidence: a Guide to Methods. Maidenhead: Open University Press; 2007. [ Google Scholar ]
• Thorne S, Jenson L, Kearney MH, Noblit G, Sandelowski M. Qualitative metasynthesis: reflections on methodological orientation and ideological agenda. Qual Health Res. 2004; 14 :1342–1365. doi: 10.1177/1049732304269888. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Centre for Reviews and Dissemination. Systematic Reviews. CRD's Guidance for Undertaking Reviews in Health Care. York: CRD; 2008. [ Google Scholar ]
• Noblit GW, Hare RD. Meta-Ethnography: Synthesizing Qualitative Studies. London: Sage; 1988. [ Google Scholar ]
• Strike K, Posner G. In: Knowledge Structure and Use. Ward S, Reed L, editor. Philadelphia: Temple University Press; 1983. Types of synthesis and their criteria. [ Google Scholar ]
• Turner S. Sociological Explanation as Translation. New York: Cambridge University Press; 1980. [ Google Scholar ]
• Britten N, Campbell R, Pope C, Donovan J, Morgan M, Pill R. Using meta-ethnography to synthesis qualitative research: a worked example. J Health Serv Res. 2002; 7 :209–15. doi: 10.1258/135581902320432732. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Campbell R, Pound P, Pope C, Britten N, Pill R, Morgan M, Donovan J. Evaluating meta-ethnography: a synthesis of qualitative research on lay experiences of diabetes and diabetes care. Soc Sci Med. 2003; 65 :671–84. doi: 10.1016/S0277-9536(02)00064-3. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Pound P, Britten N, Morgan M, Yardley L, Pope C, Daker-White G, Campbell R. Resisting medicines: a synthesis of qualitative studies of medicine taking. Soc Sci Med. 2005; 61 :133–155. doi: 10.1016/j.socscimed.2004.11.063. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Schutz A. Collected Paper. Vol. 1. The Hague: Martinus Nijhoff; 1962. [ Google Scholar ]
• Sandelowski M, Barroso J. Handbook for Synthesizing Qualitative Research. New York: Springer Publishing Company; 2007. [ Google Scholar ]
• Kearney MH. Enduring love: a grounded formal theory of women's experience of domestic violence. Research Nurs Health. 2001; 24 :270–82. doi: 10.1002/nur.1029. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Eaves YD. A synthesis technique for grounded theory data analysis. J Adv Nurs. 2001; 35 :654–63. doi: 10.1046/j.1365-2648.2001.01897.x. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Finfgeld D. Courage as a process of pushing beyond the struggle. Qual Health Res. 1999; 9 :803–814. doi: 10.1177/104973299129122298. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Glaser BG, Strauss AL. The Discovery of Grounded Theory: Strategies for Qualitative Research. New York: Aldine De Gruyter; 1967. [ Google Scholar ]
• Strauss AL, Corbin J. Basics of Qualitative Research: Grounded Theory Procedures and Techniques. Newbury Park, CA: Sage; 1990. [ Google Scholar ]
• Strauss AL, Corbin J. Basics of Qualitative Research: Techniques and Procedures for Developing Grounded Theory. Thousand Oaks, CA: Sage; 1998. [ Google Scholar ]
• Charmaz K. In: Contemporary Field Research: A Collection of Readings. Emerson RM, editor. Waveland Press: Prospect Heights, IL; 1983. The grounded theory method: an explication and interpretation; pp. 109–126. [ Google Scholar ]
• Chesler MA. Professionals' Views of the Dangers of Self-Help Groups: Explicating a Grounded Theoretical Approach. [Michigan]: Department of Sociology, University of Michigan, Ann Arbour Centre for Research on Social Organisation, Working Paper Series; 1987. [ Google Scholar ]
• Kearney MH. Ready-to-wear: discovering grounded formal theory. Res Nurs Health. 1988; 21 :179–186. doi: 10.1002/(SICI)1098-240X(199804)21:2<179::AID-NUR8>3.0.CO;2-G. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Thomas J, Harden A. Methods for the thematic synthesis of qualitative research in systematic reviews. BMC Med Res Meth. 2008; 8 :45. doi: 10.1186/1471-2288-8-45. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Lucas PJ, Arai L, Baird, Law C, Roberts HM. Worked examples of alternative methods for the synthesis of qualitative and quantitative research in systematic reviews. BMC Med Res Meth. 2007; 7 (4) [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Harden A, Garcia J, Oliver S, Rees R, Shepherd J, Brunton G, Oakley A. Applying systematic review methods to studies of people's views: an example from public health research. J Epidemiol Community H. 2004; 58 :794–800. doi: 10.1136/jech.2003.014829. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Paterson BL, Thorne SE, Canam C, Jillings C. Meta-Study of Qualitative Health Research. A Practical Guide to Meta-Analysis and Meta-Synthesis. Thousand Oaks, CA: Sage Publications; 2001. [ Google Scholar ]
• Zhao S. Metatheory, metamethod, meta-data-analysis: what, why and how? Sociol Perspect. 1991; 34 :377–390. [ Google Scholar ]
• Ritzer G. Metatheorizing in Sociology. Lexington, MA: Lexington Books; 1991. [ Google Scholar ]
• CASP (Critical Appraisal Skills Programme) http://www.phru.nhs.uk/Pages/PHD/CASP.htm date unknown.
• Greenhalgh T, Robert G, Macfarlane F, Bate P, Kyriakidou O, Peacock R. Storylines of research in diffusion of innovation: a meta-narrative approach to systematic review. Soc Sci Med. 2005; 61 :417–30. doi: 10.1016/j.socscimed.2004.12.001. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Kuhn TS. The Structure of Scientific Revolutions. Chicago: University of Chicago Press; 1962. [ Google Scholar ]
• Dixon-Woods M, Cavers D, Agarwal S, Annandale E, Arthur A, Harvey J, Hsu R, Katbamna S, Olsen R, Smith L, Riley R, Sutton AJ. Conducting a critical interpretive synthesis of the literature on access to healthcare by vulnerable groups. BMC Med Res Meth. 2006; 6 (35) [ PMC free article ] [ PubMed ] [ Google Scholar ]
• Gough D. In: Applied and Practice-based Research. 2. Furlong J, Oancea A, editor. Vol. 22. Special Edition of Research Papers in Education; 2007. Weight of evidence: a framework for the appraisal of the quality and relevance of evidence; pp. 213–228. [ Google Scholar ]
• Webb EJ, Campbell DT, Schwartz RD, Sechrest L. Unobtrusive Measures. Chicago: Rand McNally; 1966. [ Google Scholar ]
• Denzin NK. The Research Act: a Theoretical Introduction to Sociological Methods. New York: McGraw-Hill; 1978. [ Google Scholar ]
• Banning J. Ecological Triangulation. http://mycahs.colostate.edu/James.H.Banning/PDFs/Ecological%20Triangualtion.pdf
• Banning J. Ecological Sentence Synthesis. http://mycahs.colostate.edu/James.H.Banning/PDFs/Ecological%20Sentence%20Synthesis.pdf
• Brunton G, Oliver S, Oliver K, Lorenc T. A Synthesis of Research Addressing Children's, Young People's and Parents' Views of Walking and Cycling for Transport. London: EPPI-Centre, Social Science Research Unit, Institute of Education, University of London; 2006. [ Google Scholar ]
• Oliver S, Rees R, Clarke-Jones L, Milne R, Oakley A, Gabbay J, Stein K, Buchanan P, Gyte G. A multidimensional conceptual framework for analysing public involvement in health services research. Health Expect. 2008; 11 :72–84. doi: 10.1111/j.1369-7625.2007.00476.x. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Pope C, Ziebland S, Mays N. Qualitative research in health care: analysing qualitative data. BMJ. 2000; 320 :114–116. doi: 10.1136/bmj.320.7227.114. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Ritchie J, Spencer L. In: Analysing Qualitative Data. Bryman A, Burgess R, editor. London: Routledge; 1993. Qualitative data analysis for applied policy research; pp. 173–194. [ Google Scholar ]
• Miles M, Huberman A. Qualitative Data Analysis. London: Sage; 1984. [ Google Scholar ]
• Evans D, Fitzgerald M. Reasons for physically restraining patients and residents: a systematic review and content analysis. Int J Nurs Stud. 2002; 39 :739–743. doi: 10.1016/S0020-7489(02)00015-9. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Suikkala A, Leino-Kilpi H. Nursing student-patient relationships: a review of the literature from 1984–1998. J Adv Nurs. 2000; 33 :42–50. doi: 10.1046/j.1365-2648.2001.01636.x. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Weed M. 'Meta-interpretation': a method for the interpretive synthesis of qualitative research. Forum: Qual Soc Res. 2005; 6 :Art 37. [ Google Scholar ]
• Gough D, Thomas J. Dimensions of difference in systematic reviews. http://www.ncrm.ac.uk/RMF2008/festival/programme/sys1
• Spencer L, Ritchie J, Lewis J, Dillon L. Quality in Qualitative Evaluation: a Framework for Assessing Research Evidence. London: Government Chief Social Researcher's Office; 2003. [ Google Scholar ]
• Banning J. Design and Implementation Assessment Device (DIAD) Version 0.3: A response from a qualitative perspective. http://mycahs.colostate.edu/James.H.Banning/PDFs/Design%20and%20Implementation%20Assessment%20Device.pdf
• Paterson BL. In: Reviewing Research Evidence for Nursing Practice. Webb C, Roe B, editor. [Oxford]: Blackwell Publishing Ltd; 2007. Coming out as ill: understanding self-disclosure in chronic illness from a meta-synthesis of qualitative research; pp. 73–83. [ Google Scholar ]

Synthesis in Research: Home

What is synthesis?

Synthesizing information is the opposite of analyzing information. When you read an article or book, you have to pull out specific concepts from the larger document in order to understand it. This is analyzing.

When you synthesize information, you take specific concepts and consider them together to understand how they compare/contrast and how they relate to one another. Synthesis involves combining multiple elements to create a whole.

In regard to course assignments, the  elements  refer to the outside sources you've gathered to support the ideas you want to present. The  whole  then becomes your conclusion(s) about those sources.

How do I synthesize information?

Note: These steps offer a guideline, but do what works for you best.

• This is where you really decide if you want to read specific materials
• If you have gathered a substantial amount of literature and reading all of it would prove overwhelming, read the abstracts to get a better idea of the content, then select the materials that would best support your assignment
• Describe and analyze the findings and/or the author's main ideas
• What's the author's message?
• What evidence do they use to support their message?
• What does the author want a reader to understand?
• What is the larger impact of the author's message?
• Compare and contrast the main ideas and other pertinent information you found in each source
• Evaluate the quality and significance of these main ideas
• Interpret the main ideas in the context of your research question or assignment topic
• This is the step where your synthesis of the information will lead to logical conclusions about that information
• These conclusions should speak directly to your research question (i.e. your question should have an answer)

I would like to give credit to Aultman Health Sciences Library.  Most of the information used to create this guide is from their English Research libguide .

• Last Updated: Apr 8, 2024 2:29 PM
• URL: https://library.defiance.edu/synthesis

Pilgrim Library :   

   419-783-2481      ,    library@ defiance.edu       ,   click the purple "ask us" side tab above.

Synthesis and Making Connections for Strong Analysis

by acburton | Apr 25, 2024 | Resources for Students , Writing Resources

If Russian Dolls Aren’t For You, Here Are a Few Other Ways to Think About Synthesis

‘Joining the Conversation’: When we perform synthesis in our writing and engage with making connections, we are joining a wider conversation. We are seeing what has already been said about the topic, seeking out what these many perspectives and viewpoints have in common and/or how they differ, and then interpreting these relationships to form our own input to the conversation. We must directly engage with our sources to draw insightful conclusions and share what we think as a result. ‘Building the Bridge’: Synthesis is building the bridge between your sources for the reader. To synthesize or make connections, we must figure out how we get from one source to the other. In other words, we cannot present our sources in isolation (this wouldn’t help create any new meaning). Instead, we need to build the bridge between source A and source B so that our readers can understand what the two, together, suggest about our understanding of a topic. Then, we build a bridge from this new understanding to source C and source D, and so on.

Start Synthesizing

So you want to synthesize information? To start, review the existing literature on your selected topic. When searching for resources, aim to collect a number from various authors, subjects, and settings to broaden your understanding of the material – giving yourself more information to consider in the next stage. Ultimately, you’ll want to find the main idea presented in each source, as well as how the author supports or argues against it, as well as why.

• Compare and Contrast

Compare and contrast the main idea found in each source reviewed. What does each perspective have in common? What are their differences? Begin to consider how these sources  ‘fit together’ (or, in other words, build the bridge!). During this stage, you may find that some of your collected resources don’t have as much depth or go into as much detail as you’d like. That’s okay, but you’ll want to consider what effect this might have on your ability to draw a meaningful conclusion once synthesized with other source material.

• Ask, What’s the Significance?

By evaluating the quality and significance of each source, you can begin to consider its relevance within the context of your research or in relation to your topic. How does the relationship of one source to another further your understanding of the topic you are focusing on? What is the larger impact of what is being said or argued?

• Infer the Relationship and Draw Conclusions

By this point, you have gone through the existing literature surrounding your subject and compared/contrasted it, finding the main idea of each, as well as their intended purpose, possible criticisms, strengths, and weaknesses. Finally, you have related these ideas to your own research. Although you may have found that your sources agree or disagree on minor (or major) key details, it is the writer’s job to seek the relationship between these sources, put them in conversation together, and draw meaning through analysis. In some cases, you’ll be asked to offer your own perspective or argumentation. Consider, how might you add to the existing conversation?

Synthesis is all about meaningful connections, it is not summarizing sources side by side. Before you make larger claims about a topic, make sure you build those bridges between the sources you found through research. Nestle them together. Move beyond summary. Then, you can create an interesting and compelling argument. For additional help, make an appointment with the Writing Center!

Works Cited

Kourakos, Evanthia J. “The Matryoshka-Doll Effect.”  Medium , Azure’s Whereabouts, 22 Apr. 2016,  medium.com/azure-s- whereabouts/the-matryoshka- doll-effect-be9d2760d2e2 .Acces sed 25 Apr. 2024.

“Libguides: English Research: Synthesizing Information.”  Synthesizing Information – English Research – LibGuides at Aultman Health Sciences Library ,  aultman.libguides.com/c.php?g= 545558&p=7711993 . Accessed 25 Apr. 2024.

Libraries | Research Guides

Evidence synthesis.

• Evidence Synthesis Overview
• Evidence Synthesis Resources by Discipline

1. Develop a Research Question and Apply a Framework

2. select a reporting guideline, 3. select databases, 4. select grey literature sources, 5. write a search strategy, 6. register a protocol, 7. translate search strategies, 8. manage your citations, 9. article screening, 10. assess the risk of bias, 11. extract the data, 12. synthesize, map, or describe the results.

• Quantitative Studies (PICO)
• Qualitative Studies (PICo, CHIP)
• Mixed Methods (SPICE, SPIDER)
• Scoping Reviews (PCC)

Formulating a research question is key to a systematic review. It will be the foundation upon which the rest of the research is built. At this stage in the process, you will have identified a knowledge gap in your field, and you are aiming to answer a specific question. For example:

If X is prescribed, what happens to Y patients?

or assess and intervention:

How does X affect Y?

or synthesize existing evidence:

What is the nature of X?

Developing a research question takes time. You will likely go through different versions before settling on a final question. Once you've developed your research question, you will use it to create a search strategy.

Frameworks help to break your question into parts so you can clearly see the elements of your topic. Depending on your field of study, the frameworks listed in this guide may not fit the types of questions you're asking. There are dozens of frameworks you can use to formulate your specific and answerable research question. To see other frameworks you might use, visit the  University of Maryland's Systematic Review guide.

The most common framework for systematic reviews is PICO, which is often used within the health sciences for clinical research, or in education. It is commonly used for quantitative studies.

P: Population

I: Intervention/Exposure

C: Comparison

Example:  In 11-12 year old children (Population), what is the effect of a school-based multi-media learning program  (Intervention) on an increase in real-world problem solving skills compared with analog-only curriculum  (Comparison) within a one-year period (Time)?

Source:  Richardson, W. S., Wilson, M. C., Nishikawa, J., & Hayward, R. S. (1995).  The well-built clinical question: A key to evidence-based decisions .  ACP journal club, 123 (3), A12-A12.

P: Population/problem

I: Phenomenon of Interest

Co: Context

Example:  What are the  experiences  (phenomenon of interest) of  caregivers providing home based care to patients with Alzheimer's disease  (population) in  Australia  (context)?

Source:  Methley, A.M., Campbell, S., Chew-Graham, C.  et al.  PICO, PICOS and SPIDER: a comparison study of specificity and sensitivity in three search tools for qualitative systematic reviews.  BMC Health Serv Res   14,  579 (2014). https://doi.org/10.1186/s12913-014-0579-0

________________________________________________________________________

Example: 

Source:  Shaw, R. (2010).  Conducting literature reviews . In M. A. Forester (Ed.),  Doing Qualitative Research in Psychology: A Practical  Guide  (pp. 39-52). London, Sage.

P: Perspective

I: Intervention/Exposure/Interest

C : Comparison

E: Evaluation

Example:  What are the  benefits  (evaluation) of a  doula  (intervention) for  low income mothers  (perspective) in the  developed world  (setting) compared to  no support  (comparison)?

Source:  Booth, A. (2006). Clear and present questions: Formulating questions for evidence based practice.  Library Hi Tech, 24 (3), 355-368.   https://doi.org/10.1108/07378830610692127

________________________________________________________

PI: Phenomenon of Interest

R: Research Type

Example:  What are the  experiences  (evaluation) of  women  (sample) undergoing  IVF treatment  (phenomenon of interest) as assessed?

Design:   questionnaire or survey or interview

Study Type:  qualitative or mixed method

Source:  Cooke, A., Smith, D., & Booth, A. (2012). Beyond PICO: The SPIDER tool for qualitative evidence synthesis.  Qualitative Health Research, 22 (10), 1435-1443.  https://doi.org/10.1177/1049732312452938

Scoping reviews generally have a broader scope that systematic reviews, but it is still helpful to put scoping and mapping reviews within a framework. The Joanna Briggs Institute offers guidance on forming scoping review questions in Chapter 11 of their manual for evidence synthesis . They recommend using the PCC framework:

Example:  What are the trends (concept) in MOOCs (context) that support the interactions of learners with disabilities (population)?

Source:  Peters MDJ, Godfrey C, McInerney P, Munn Z, Tricco AC, Khalil, H. Chapter 11: Scoping Reviews (2020 version). In: Aromataris E, Munn Z (Editors). JBI Manual for Evidence Synthesis, JBI, 2020. Available from  https://synthesismanual.jbi.global .   https://doi.org/10.46658/JBIMES-20-12

• MARS Meta-Analysis reporting standards From the American Psychological Association (APA).
• MECCIR (Methodological Expectations of Campbell Collaboration Intervention Reviews) Links to site to download reporting standards for reviews in the social sciences and education.
• PRISMA A 27-item checklist. PRISMA guidelines are used primarily by those within the health sciences.
• PRISMA ScR The PRISMA Scoping Review checklist. Created for the health sciences, but can be used across disciplines.

Librarians can assist you with selecting databases for your systematic review. Each database is different and will require a different search syntax. Some databases have controlled vocabulary and thesauri that you will want to incorporate into your searches. We recommend creating one master search strategy and then translating it for each database. 

To begin browsing databases, visit the A-Z Database List:

• A-Z Databases A-Z list of databases available through the Northwestern University Libraries.
• Northwestern Research Guides Created by Northwestern Librarians, research guides are curated lists of databases and resources for each discipline.
• What is Grey Literature?
• Why Search Grey Literature?
• How do I search Grey Literature?
• Sources for Grey Literature

Grey (or gray) Literature is "A variety of written materials produced by organizations outside of traditional commercial and academic publishing channels, such as annual reports, [theses and dissertations], white papers, or conference proceedings from government agencies, non-governmental organizations, or private companies. Grey literature may be difficult to access because it may not be widely distributed or included in bibliographic databases." 

Your research question and field of study will guide what type of grey literature to include in your systematic review. 

Source: Byrne, D. (2017). Reviewing the literature.  Project Planner . 10.4135/9781526408518.

The purpose of a systematic review is to identify and synthesize all available evidence. There is significant bias in scientific publishing toward publishing studies that show some sort of significant effect. In fact, according to Campbell Collaboration Guidelines on Information Retrieval , more than 50% of studies reported in conference abstracts never reach full publication. While conference abstracts and other grey literature is not peer-reviewed, it is important to include all available research on the topic you're studying.

Finding grey literature on your topic may require some creativity, and may involve going directly to the source. Here are a few tips:

• Find a systematic review on a topic similar to yours and see what grey literature sources they used. You can find existing systematic reviews in subject databases, The Campbell Library, and the Cochrane Library. In databases such as PsycINFO, you can use the Methodology search tool to narrow by Systematic Review or Meta-Analysis; otherwise check the thesaurus for controlled vocabulary or use the keyword search to add ("systematic review" OR meta-analysis OR "scoping review") to your search string.
• Ask colleagues and other experts in the field for sources of grey literature in your discipline.
• Contact known researchers in the field to learn if there are any unpublished or ongoing studies to be aware of.
• On the web, search professional associations, research funders, and government websites.
• ProQuest Dissertations & Theses Global This link opens in a new window With more than 2 million entries, PQD&T offers comprehensive listings for U.S. doctoral dissertations back to 1861, with extensive coverage of dissertations from many non-U.S. institutions. A number of masters theses are also listed. Thousands of dissertations are available full text, and abstracts are included for dissertations from the mid-1980s forward.
• Networked Digital Library of Theses and Dissertations (NDLTD) An international organization dedicated to promoting the adoption, creation, use, dissemination, and preservation of electronic theses and dissertations (ETDs).
• WHO Institutional Repository for Resource Sharing Institutional WHO database of intergovernmental policy documents and technical reports. Can search by IRIS by region (Africa, Americas, Eastern Mediterranean, Europe, South-East Asia, Western Pacific)
• OCLC PapersFIrst OCLC index of papers presented at conferences worldwide
• OSF Preprints Center for Open Science Framework's search tool for scholarly preprints in the fields of architecture, arts, business, social and behavioral science, and more.
• Directory of Open Access Repositories Global Directory of Open Access Repositories. You can search and browse through thousands of registered repositories based on a range of features, such as location, software or type of material held.
• Social Science Research Network This link opens in a new window A service providing scholarly research papers, working papers, and journals in numerous social science disciplines. Includes the following: Accounting Research Network, Cognitive Science Network, Economics Research Network, Entrepreneurship Research & Policy Network, Financial Economics Network, Legal Scholarship Network, Management Research Network.

Use the keywords from your research question and begin to create a core keyword search that can then be translated to fit each database search. Since the goal is to be as comprehensive as possible, you will want to identify all terms that may be used for each of the keywords, and use a combination of natural language and controlled vocabulary when available. Librarians are available to assist with search strategy development and keyword review.

Your core keyword search will likely include some or all of the following syntax:

• Boolean operators (AND, OR, and NOT) 
• Proximity operators (NEAR or WITHIN)
• Synonyms, related terms, and alternate spellings
• Controlled vocabulary (found within the database thesaurus)
• Truncation (ex: preg* would find pregnant and pregnancy)

Search filters that are built into databases may also be used, but use them with caution. Database articles within the social sciences tend not to be as consistently or thoroughly indexed as those within the health sciences, so using filters could cause you to miss some relevant results.

Source:  Kugley S, Wade A, Thomas J, Mahood Q, Jørgensen AMK, Hammerstrøm K, Sathe N. Searching for studies: A guide to information retrieval for Campbell Systematic Reviews . Campbell Methods Guides 2016:1 DOI: 10.4073/cmg.2016.1

• Recording Synonyms Worksheet Template you can use when creating lists of search terms.
• SnowGlobe A program that assists with literature searching, SnowGlobe takes all known relevant papers and searches through their references (which papers they cite) and citations (which papers cite them).

A protocol is a detailed explanation of your research project that should be written before you begin searching. It will likely include your research question, objectives, and search methodology, but information included within a protocol can vary across disciplines. The protocol will act as a map for you and your team, and will be helpful in the future if you or any other researchers want to replicate your search. Protocol development resources and registries:

• PRISMA-P A checklist of recommended items for inclusion within a systematic review protocol.
• Evidence Synthesis Protocol Template Developed by Cornell University Library, the protocol template is a useful tool that can be used to begin writing your protocol.
• Campbell Collaboration: Submit a Proposal The Campbell Collaboration follows MECCIR reporting standards. If you register with Campbell, you are agreeing to publish the completed review with Campbell first. According to the title registration page, "Co-publication with other journals is possible only after discussing with the Campbell Coordinating Group and Editor in Chief." more... less... Disciplines: Business and Management, Crime and Justice, Disability, Education, International Development, Knowledge Translation and Implementation, Methods, Nutrition, and Social Welfare
• PROSPERO registry "PROSPERO accepts registrations for systematic reviews, rapid reviews and umbrella reviews. PROSPERO does not accept scoping reviews or literature scans." more... less... Disciplines: health sciences and social care
• Open Science Framework (OSF) registry If your review doesn't fit into one of the major registries, consider using Open Science Framework. OSF can be used to pre-register a systematic review protocol and to share documents such as a Zotero library, search strategies, and data extraction forms. more... less... Disciplines: multidisciplinary

Each database is different and will require a customized search string. We recommend creating one master keyword list and then translating it for each database by using that database's subject terms and search syntax. Below are some tools to assist with translating search strings from one database to the next.

• Translating Search Strategies Template Created at Cornell University Library
• Database Syntax Guide (Cochrane) Includes syntax for Cochrane Library, EBSCO, ProQuest, Ovid, and POPLINE.
• Systematic Review Search Translator The IEBH SR-Accelerator is a suite of tools to speed up steps in the Systematic Review (SR) process.

When conducting a systematic review, you will likely be exporting hundreds or even thousands of citations from databases. Citation management tools are useful for storing, organizing, and managing your citations. They can also perform de-duplication to remove doubles of any citations you may have. The Libraries provide training and support on EndNote, Zotero, and Mendeley. Visit the links below to get started. You may also reach out directly to  [email protected]  with questions or consultation requests.

• EndNote Support Guide
• Mendeley Support Guide
• Zotero Support Guide

During the screening process, you will take all of the articles you exported from your searches and begin to remove studies that are not relevant to your topic. Use the inclusion/exclusion criteria you developed during the protocol-writing stage to screen the title and abstract of the articles you found. Any studies that don't fit the criteria of your review can be deleted. The full text of the remaining studies will need to be screened to confirm that they fit the criteria of your review.

It is highly recommended that two independent reviewers screen all studies, resolving areas of disagreement by consensus or by a third party who is an expert in the field. Listed below are tools that can be used for article screening.

• Rayyan A tool designed to expedite the screening process for systematic reviews. Create a free account, upload citations, and collaborate with others to screen your articles.
• Covidence A subscription based systematic review management tool that provides article screening and quality assessment features. Northwestern does not currently have a subscription, so individual/group pricing applies.

Bias refers to factors that can systematically affect the observations and conclusions of the study, causing them to be inaccurate. When compiling studies for systematic reviews, it is best practice to assess the risk of bias for each of the studies included, and then include the assessment in your final manuscript. The Cochrane Handbook recommends presenting the assessment as a table or graph.

In general, scoping reviews don't require a risk of bias assessment, but according to the PRISMA Scoping Review checklist , scoping reviews should include a "critical appraisal of individual sources of evidence." In a final manuscript, a critical appraisal could be an explanation of the limitations of the studies included.

Source: Andrea C. Tricco, Erin Lillie, Wasifa Zarin, et al.  PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation . Ann Intern Med.2018;169:467-473. [Epub ahead of print 4 September 2018]. doi: 10.7326/M18-0850

• Cochrane Training Presentation: Risk of Bias Simple overview of risk of bias assessment, including examples of how to assess and present your conclusions.
• Critical Appraisal Skills Programme (CASP) CASP has appraisal checklists designed for use with Systematic Reviews, Randomised Controlled Trials, Cohort Studies, Case Control Studies, Economic Evaluations, Diagnostic Studies, Qualitative studies and Clinical Prediction Rule.
• JBI Critical Appraisal Tools From the Joanna Briggs Institute: "JBI’s critical appraisal tools assist in assessing the trustworthiness, relevance and results of published papers."

Once you and your team have screened all of the studies to be included in your review, you will need to extract the data from the studies in order to synthesize the results. You can use Excel or Google Forms to code the results. Additional resources below.

• Covidence: Data Extraction Covidence is a software that manages all aspects of systematic review processes, including data extraction. Northwestern does not currently subscribe to Covidence, so individual subscription rates apply.
• Data Extraction Form Template (Excel)
• RevMan Short for "review manager," RevMan is a free software used to manage Cochrane systematic reviews. It can assist with data extraction and analysis, including meta-analysis.
• SR Toolbox "a web-based catalogue of tools that support various tasks within the systematic review and wider evidence synthesis process."
• Systematic Review Data Repository "The Systematic Review Data Repository (SRDR) is a powerful and easy-to-use tool for the extraction and management of data for systematic review or meta-analysis."
• A Practical Guide: Data Extraction for Intervention Systematic Reviews' "This guide provides you with insights from the global systematic review community, including definitions, practical advice, links to the Cochrane Handbook, downloadable templates, and real-world examples." -Covidence Free ebook download (must enter information to download the title for free)

In the data synthesis section, you will present the main findings of your evidence synthesis. There are multiple ways you could go about synthesizing the data, and that decision will depend largely on the type of studies you're synthesizing. In any case, it is standard to use the PRISMA flow diagram to map out the number of studies identified, screened, and included in your evidence synthesis project.

Librarians can help write the methods section of your review for publication, to ensure clarity and transparency of the search process. However, we encourage evidence synthesis teams to engage statisticians to carry out their data syntheses.

• PRISMA Flow Diagram
• PRISMA Flow Diagram Creator

Meta-Analysis

A quantitative statistical analysis that combines the results of multiple studies. The studies included must all be attempting to answer the same research question and have a similar research design. According to the  Cochrane Handbook,  "meta-analysis yields an overall statistic (together with its confidence interval) that summarizes the effectiveness of an experimental intervention compared with a comparator intervention."

• Meta-Analysis Effect Size Calculator "...a web-based effect-size calculator. It is designed to facilitate the computation of effect-sizes for meta-analysis. Four effect-size types can be computed from various input data: the standardized mean difference, the correlation coefficient, the odds-ratio, and the risk-ratio."
• Meta-Essentials A free tool for meta-analysis that "facilitates the integration and synthesis of effect sizes from different studies. The tool consists of a set of workbooks designed for Microsoft Excel that, based on your input, automatically produces all the required statistics, tables, figures, and more."
• The metafor Package "a free and open-source add-on for conducting meta-analyses with the statistical software environment R."

Narrative or Descriptive

If you've included studies that are not similar in research design, then a meta-analysis is not possible. You will then use a narrative or descriptive synthesis to describe the results.

• << Previous: Evidence Synthesis Resources by Discipline
• Last Updated: Mar 12, 2024 9:37 AM
• URL: https://libguides.northwestern.edu/evidencesynthesis

Should I do a synthesis (i.e. literature review)?

• Questions & Quandaries
• Published: 18 April 2024

Cite this article

• H. Carrie Chen 1 ,
• Ayelet Kuper 2 , 3 , 4 ,
• Jennifer Cleland 5 &
• Patricia O’Sullivan 6  

249 Accesses

1 Altmetric

Explore all metrics

This column is intended to address the kinds of knotty problems and dilemmas with which many scholars grapple in studying health professions education. In this article, the authors address the question of whether one should conduct a literature review or knowledge synthesis, considering the why, when, and how, as well as its potential pitfalls. The goal is to guide supervisors and students who are considering whether to embark on a literature review in education research.

Avoid common mistakes on your manuscript.

Two junior colleagues come to you to ask your advice about carrying out a literature review on a particular topic. “Should they?” immediately pops into your mind, followed closely by, if yes, then what kind of literature review is appropriate? Our experience is that colleagues often come to suggest a literature review to “kick start” their research (in fact, some academic programs require them as part of degree requirements), without a full understanding of the work involved, the different types of literature review, and what type of literature review might be most suitable for their research question. In this Questions and Quandaries, we address the question of literature reviews in education research, considering the why, when, and how, as well as potential pitfalls.

First, what is meant by literature review? The term literature review has been used to refer to both a review of the literature and a knowledge synthesis (Maggio et al., 2018 ; Siddaway et al., 2019 ). For our purposes, we employ the term as commonly used to refer to a knowledge synthesis , which is a formal comprehensive review of the existing body of literature on a topic. It is a research approach that critically integrates and synthesizes available evidence from multiple studies to provide insight and allow the drawing of conclusions. It is an example of Boyer’s scholarship of integration (Boyer, 1990 ). In contrast, a review of the literature is a relatively casual and expedient method for attaining a general overview of the state of knowledge on a given topic to make the argument that a new study is needed. In this interpretation, a literature review serves as a key starting point for anyone conducting research by identifying gaps in the literature, informing the study question, and situating one’s study in the field.

Whether a formal knowledge synthesis should be done depends on if a review is needed and what the rationale is for the review. The first question to consider is whether a literature review already exists. If no, is there enough literature published on the topic to warrant a review? If yes, does the previous review need updating? How long has it been since the last review and has the literature expanded so much or are there important new studies that need integrating to justify an updated review? Or were there flaws in the previous review that one intends to address with a new review? Or does one intend to address a different question than the focus of the previous review?

If the knowledge synthesis is to be done, it should be driven by a research question. What is the research question? Can it be answered by a review? What is the purpose of the synthesis? There are two main purposes for knowledge synthesis– knowledge support and decision support. Knowledge support summarizes the evidence while decision support takes additional analytical steps to allow for decision-making in particular contexts (Mays et al., 2005 ).

If the purpose is to provide knowledge support, then the question is how or what will the knowledge synthesis add to the literature? Will it establish the state of knowledge in an area, identify gaps in the literature/knowledge base, and/or map opportunities for future research? Cornett et al., performed a scoping review of the literature on professional identity, focusing on how professional identity is described, why the studies where done, and what constructs of identity were used. Their findings advanced understanding of the state of knowledge by indicating that professional identity studies were driven primarily by the desire to examine the impact of political, social and healthcare reforms and advances, and that the various constructs of professional identity across the literature could be categorized into five themes (Cornett et al., 2023 ).

If, on the other hand, the purpose of the knowledge synthesis is to provide decision support, for whom will the synthesis be relevant and how will it improve practice? Will the synthesis result in tools such as guidelines or recommendations for practitioners and policymakers? An example of a knowledge synthesis for decision support is a systematic review conducted by Spencer and colleagues to examine the validity evidence for use of the Ottawa Surgical Competency Operating Room Evaluation (OSCORE) assessment tool. The authors summarized their findings with recommendations for educational practice– namely supporting the use of the OSCORE for in-the-moment entrustment decisions by frontline supervisors in surgical fields but cautioning about the limited evidence for support of its use in summative promotions decisions or non-surgical contexts (Spencer et al., 2022 ).

If a knowledge synthesis is indeed appropriate, its methodology should be informed by its research question and purpose. We do not have the space to discuss the various types of knowledge synthesis except to say that several types have been described in the literature. The five most common types in health professions education are narrative reviews, systematic reviews, umbrella reviews (meta-syntheses), scoping reviews, and realist reviews (Maggio et al., 2018 ). These represent different epistemologies, serve different review purposes, use different methods, and result in different review outcomes (Gordon, 2016 ).

Each type of review lends itself best to answering a certain type of research question. For instance, narrative reviews generally describe what is known about a topic without necessarily answering a specific empirical question (Maggio et al., 2018 ). A recent example of a narrative review focused on schoolwide wellbeing programs, describing what is known about the key characteristics and mediating factors that influence student support and identifying critical tensions around confidentiality that could make or break programs (Tan et al., 2023 ). Umbrella reviews, on the other hand, synthesize evidence from multiple reviews or meta-analyses and can illuminate agreement, inconsistencies, or evolution of evidence on a topic. For example, an umbrella review on problem-based learning highlighted the shift in research focus over time from does it work, to how does it work, to how does it work in different contexts, and pointed to directions for new research (Hung et al., 2019 ).

Practical questions for those considering a literature review include whether one has the time required and an appropriate team to conduct a high-quality knowledge synthesis. Regardless of the type of knowledge synthesis and use of quantitative or qualitative methods, all require rigorous and clear methods that allow for reproducibility. This can take time, up to 12–18 months. A high-quality knowledge synthesis also requires a team whose members have expertise not only in the content matter, but also in knowledge synthesis methodology and in literature searches (i.e. a librarian). A team with multiple reviewers with a variety of perspectives can also help manage the volume of large reviews, minimize potential biases, and strengthen the critical analysis.

Finally, a pitfall one should be careful to avoid is merely summarizing everything in the literature without critical evaluation and integration of the information. A knowledge synthesis that merely bean counts or presents a collection of unconnected information that has not been reflected upon or critically analyzed does not truly advance knowledge or decision-making. Rather, it leads us back to our original question of whether it should have been done in the first place.

Boyer, E. L. (1990). Scholarship reconsidered: Priorities of the professoriate (pp. 18–21). Princeton University Press.

Cornett, M., Palermo, C., & Ash, S. (2023). Professional identity research in the health professions—a scoping review. Advances in Health Sciences Education , 28 (2), 589–642.

Article   Google Scholar  

Gordon, M. (2016). Are we talking the same paradigm? Considering methodological choices in health education systematic review. Medical Teacher , 38 (7), 746–750.

Hung, W., Dolmans, D. H. J. M., & van Merrienboer, J. J. G. (2019). A review to identify key perspectives in PBL meta-analyses and reviews: Trends, gaps and future research directions. Advances in Health Sciences Education , 24 , 943–957.

Maggio, L. A., Thomas, A., & Durning, S. J. (2018). Knowledge synthesis. In T. Swanwick, K. Forrest, & B. C. O’Brien (Eds.), Understanding Medical Education: Evidence, theory, and practice (pp. 457–469). Wiley.

Mays, N., Pope, C., & Popay, J. (2005). Systematically reviewing qualitative and quantitative evidence to inform management and policy-making in the health field. Journal of Health Services Research & Policy , 10 (1_suppl), 6–20.

Siddaway, A. P., Wood, A. M., & Hedges, L. V. (2019). How to do a systematic review: A best practice guide for conducting and reporting narrative reviews, meta-analyses, and meta-syntheses. Annual Review of Psychology , 70 , 747–770.

Spencer, M., Sherbino, J., & Hatala, R. (2022). Examining the validity argument for the Ottawa Surgical Competency operating room evaluation (OSCORE): A systematic review and narrative synthesis. Advances in Health Sciences Education , 27 , 659–689.

Tan, E., Frambach, J., Driessen, E., & Cleland, J. (2023). Opening the black box of school-wide student wellbeing programmes: A critical narrative review informed by activity theory. Advances in Health Sciences Education . https://doi.org/10.1007/s10459-023-10261-8 . Epub ahead of print 02 July 2023.

Download references

Author information

Authors and affiliations.

Georgetown University School of Medicine, Washington, DC, USA

H. Carrie Chen

Wilson Centre for Research in Education, University Health Network, University of Toronto, Toronto, Canada

Ayelet Kuper

Division of General Internal Medicine, Sunnybrook Health Sciences Center, Toronto, Canada

Department of Medicine, University of Toronto, Toronto, Canada

Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore

Jennifer Cleland

University of California San Francisco School of Medicine, San Francisco, CA, USA

Patricia O’Sullivan

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to H. Carrie Chen .

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Chen, H.C., Kuper, A., Cleland, J. et al. Should I do a synthesis (i.e. literature review)?. Adv in Health Sci Educ (2024). https://doi.org/10.1007/s10459-024-10335-1

Download citation

Published : 18 April 2024

DOI : https://doi.org/10.1007/s10459-024-10335-1

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Find a journal
• Publish with us
• Track your research

REVIEW article

This article is part of the research topic.

Vol II: Person-Centred Rehabilitation – Theory, Practice and Research

Hope as experienced by people with acquired brain injury in a rehabilitationor recovery process: A qualitative systematic review and thematic synthesis Provisionally Accepted

• 1 Aalborg University, Denmark
• 2 Municipality of Copenhagen, Denmark

The final, formatted version of the article will be published soon.

Background: There has been an increasing interest in the concept of hope within the field of brain injury rehabilitation. Existing reviews have nevertheless focused on stroke, leaving out the broad populationgroup of people with acquired brain injury (ABI). Furthermore a just as majority of the included studies in those reviews excluded the subgroup of people with communication difficulties, thus primarily giving voice to a select group of people with ABI. Methods: A qualitative systematic review was conducted with the purpose of systematically reviewing and thematically synthesise findings about hope as experienced by adultspeople with ABI in a rehabilitation or recovery process. The search strategy included peer-reviewed qualitative studies published after 2000 in English or Scandinavian languages. Searches of EBSCO databases incorporating CINAHL, MEDLINE, and PsycINFO were conducted together with SocINDEX, Social Work Abstracts, Eric and Web of Science. Ten qualitative studies were included, and the Critical Appraisal Skills Program (CASP) was used for assessing the quality and relevance of the ten studies. Qualitative findings were synthesized using Thomas and Harden's methodology. data were analysed based on methods for thematic synthesis by Thomas and Harden. Results: Through a thematic synthesis eleven subthemes were identifiedemerged relating to experiences of hope. These were grouped into four analytical themes: (1) Hope a two folded phenomenon; (2) Time and temporality; (3) Progress, goals and visibility and (4) The alliance. Conclusion: This review has shown that even though hope has both a positive and negative side to it, it is necessary as a driving force for people with ABI in terms of supporting them to keep going and not give up. Rehabilitation professionals are advised to embrace the ambiguity of hope, customizing the support of hope to each person with ABI. Attention is needed on how to make progress visible for persons with ABI during their rehabilitation process just as rehabilitation professionals should acknowledge the alliance with the person with ABI as a core component of rehabilitation. This requires a focus on professionals' communication skills if hope promoting relationships between professionals and persons with ABI are to be achieved.

Keywords: hope, acquired brain injury, Rehabilitation, Recovery, literature review, qualitative studies, thematic synthesis

Received: 26 Jan 2024; Accepted: 26 Apr 2024.

Copyright: © 2024 Højgaard Nejst and Glintborg. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Camilla Højgaard Nejst, Aalborg University, Aalborg, Denmark

People also looked at

• MyU : For Students, Faculty, and Staff

NSF Graduate Research Fellowship Program honors nine Chemistry student community members

MINNEAPOLIS / ST. PAUL (4/26/2023) – Nine members of the Department of Chemistry student community were recently honored with recognition by the National Science Foundation Graduate Research Fellowship Program (NSF GRFP). Briana Krupinsky, Grace Murphy, Timmy Nguyen, and Ulises Perez were awarded fellowships, and Mrinalni Iyer, Killian MacFeely, Wallee Naimi, Miles Willis, and Ali Younis received honorable mentions.

Briana Krupinsky is a second-year graduate student in the Lamb group . She joined the UMN community after completing her undergraduate studies at the University of North Dakota. Briana investigates N-hetereocyclic carbene-carbodiimide (NHC-CDI) adducts for application as catalyst precursors in organocatalysis. At the moment, this includes working towards understanding the thermodynamic and kinetic properties of NHC-CDI adducts for well-controlled catalysis. One of Briana’s research goals is to develop a light-activated NHC-CDI catalyst precursor to achieve spatiotemporal control for the synthesis of polymers.

Grace Murphy , a member of the Hoover lab , came to UMN after completing her undergraduate studies at Saint Louis University. One of her long-term goals as a chemist is to study and develop transition metal catalyzed reactions that are used in organic chemistry. She is particularly interested in understanding the structure-reactivity relationships that make difficult reactions possible. Grace is currently working towards understanding the mechanism of nickel catalyzed/mediated decarbonylation, a reaction that has potential future applications to the synthesis of pharmaceuticals to polymer upcycling.

Timmy Nguyen first came to UMN for a summer research experience program in 2022, right before his senior year at California State Polytechnic University, Pomona. He officially joined the graduate program in 2023 as a member of the Haynes group. Timmy is interested in anisotropic nanoparticles as substrates and recently started working on a project to synthesize silica-coated gold nanorods for use in SERS sensors. He is also passionate about participating in outreach activities through Science for All, a student group that works to bring the excitement of science to Minnesota middle schools.

Ulises Perez , a Spring 2023 graduate from the UMN Chemistry undergraduate program and current PhD student at University of Washington, was also awarded a fellowship.

The NSF GRFP recognizes and supports outstanding graduate students in NSF-supported science, technology, engineering, and mathematics disciplines who are pursuing research-based master’s and doctoral degrees at accredited United States institutions. The program also seeks to support the participation of underrepresented groups in STEM graduate studies.

Mrinalni Iyer, Killian MacFeely, Wallee Naimi, Miles Willis, and Ali Younis received honorable mentions for their applications. The Department of Chemistry congratulates all nine students on this significant national academic achievement!

Related news releases

• Kargbo, Pham, and Tuga receive Merck Underrepresented Chemists of Color Research Award
• Taimeng Liang awarded ACS Division of Medicinal Chemistry Predoctoral Fellowship
• Manuraj Kallumkal and Pete Gabriel Ledesma receive Pothapragada International Graduate Student Fellowship
• PhD candidate Casey Ritts receives American Cancer Society Postdoctoral Fellowship
• PhD students recognized with awards and honors at Fall Kickoff Seminar
• Future undergraduate students
• Future transfer students
• Future graduate students
• Future international students
• Diversity and Inclusion Opportunities
• Learn abroad
• Living Learning Communities
• Mentor programs
• Programs for women
• Student groups
• Visit, Apply & Next Steps
• Information for current students
• Departments and majors overview
• Departments
• Undergraduate majors
• Graduate programs
• Integrated Degree Programs
• Additional degree-granting programs
• Online learning
• Academic Advising overview
• Academic Advising FAQ
• Academic Advising Blog
• Appointments and drop-ins
• Academic support
• Commencement
• Four-year plans
• Honors advising
• Policies, procedures, and forms
• Career Services overview
• Resumes and cover letters
• Jobs and internships
• Interviews and job offers
• CSE Career Fair
• Major and career exploration
• Graduate school
• Collegiate Life overview
• Scholarships
• Diversity & Inclusivity Alliance
• Anderson Student Innovation Labs
• Information for alumni
• Get engaged with CSE
• Upcoming events
• CSE Alumni Society Board
• Alumni volunteer interest form
• Golden Medallion Society Reunion
• 50-Year Reunion
• Alumni honors and awards
• Outstanding Achievement
• Alumni Service
• Distinguished Leadership
• Honorary Doctorate Degrees
• Nobel Laureates
• Alumni resources
• Alumni career resources
• Alumni news outlets
• CSE branded clothing
• International alumni resources
• Inventing Tomorrow magazine
• Update your info
• CSE giving overview
• Why give to CSE?
• College priorities
• Give online now
• External relations
• Giving priorities
• Donor stories
• Impact of giving
• Ways to give to CSE
• Matching gifts
• CSE directories
• Invest in your company and the future
• Recruit our students
• Connect with researchers
• K-12 initiatives
• Diversity initiatives
• Research news
• Give to CSE
• CSE priorities
• Corporate relations
• Information for faculty and staff
• Administrative offices overview
• Office of the Dean
• Academic affairs
• Finance and Operations
• Communications
• Human resources
• Undergraduate programs and student services
• CSE Committees
• CSE policies overview
• Academic policies
• Faculty hiring and tenure policies
• Finance policies and information
• Graduate education policies
• Human resources policies
• Research policies
• Research overview
• Research centers and facilities
• Research proposal submission process
• Research safety
• Award-winning CSE faculty
• National academies
• University awards
• Honorary professorships
• Collegiate awards
• Other CSE honors and awards
• Staff awards
• Performance Management Process
• Work. With Flexibility in CSE
• K-12 outreach overview
• Summer camps
• Outreach events
• Enrichment programs
• Field trips and tours
• CSE K-12 Virtual Classroom Resources
• Educator development
• Sponsor an event