This guide will introduce you to systematic reviews and other types of knowledge syntheses and will connect you with some useful tools and resources.
While knowledge syntheses have long been used in the medical and health sciences fields, they are increasingly being conducted in other disciplines. Many of the resources listed in this guide originate in the medical/health sciences field, but they are included here as their applicability extends to other disciplines in the social sciences and beyond.
Knowledge Synthesis, also called evidence synthesis or research synthesis, is a broad term used to describe various types of review studies.
According to the Canadian Institutes of Health Research, Knowledge Synthesis is "the contextualization and integration of research findings of individual research studies within the larger body of knowledge on the topic. A synthesis must be reproducible and transparent in its methods, using quantitative and/or qualitative methods." Canadian Institutes of Health Research. A Guide to Knowledge Synthesis
Evidence Synthesis International provides the following description: "Evidence synthesis uses formal, explicit, and rigorous methods to bring together the findings of research already completed, to provide an account of the totality what is known from that pre-existing research." About Evidence Synthesis, Evidence Synthesis International
The terms knowledge synthesis and evidence synthesis are used interchangeably in this guide.
Systematic Reviews are one type of knowledge/evidence synthesis, but there are many others including scoping reviews, rapid reviews, and umbrella reviews.
A systematic review is a comprehensive search of existing literature that uses standardized, transparent, and reproducible methods to answer a clearly defined research question. Traditional or narrative literature reviews differ from systematic reviews in several ways as explained in the following table.
|
|
Systematic Review |
Literature Review |
|
Definition |
High-level overview of primary research on a focused question that identifies, selects, synthesizes, and appraises all high-quality research evidence relevant to that question. |
Qualitatively summarizes evidence on a topic using informal or subjective methods to collect and interpret studies. |
|
Goals |
Answer a focused question Eliminate bias |
Provide a summary or overview of a topic |
|
Question |
Clearly defined and answerable question Recommend using a question framework as a guide, such as PICO (Patient/Population/ Problem, Intervention, Comparison, Outcome). |
Can be a general topic or a specific question |
|
Components |
Pre-specified eligibility criteria Systematic search strategy Assessment of the validity of findings Interpretation and presentation of results Reference list |
Introduction Methods Discussion Conclusion Reference list |
|
Number of Authors |
Three or more |
One or more |
|
Timeline |
Months to years Average eighteen months |
Weeks to months |
|
Requirements |
Thorough knowledge of topic Perform searches of all relevant databases Statistical analysis resources (for meta-analysis) |
Understanding of topic Perform searches of one or more databases |
|
Value |
Informs evidence-based decisions and practice |
Provides summary of literature on a topic |
Adapted from Kysh, Lynn (2013). Difference between a systematic review and a literature review. Figshare. Poster. https://doi.org/10.6084/m9.figshare.766364.v1. Licensed under Creative Commons CC BY 4.0 /some changes to wording.
Traditional literature reviews are not covered in this guide. For information about traditional literature reviews, please visit the Library's Literature Review guide.
When planning to undertake a knowledge synthesis, it is essential to select a review type that is appropriate to your research question. This guide will cover some of the more common review types you may encounter. However, deciding on which type of review is right for you can be challenging. The following resources provide information and guidance on how to select the most appropriate review type for your research needs.
Systematic Approaches to a Successful Literature Review (3rd Edition) by 