Skip to Main Content

Knowledge Syntheses: A How-To Guide

Overview of systematic review steps and resources to assist researchers conducting reviews

Covidence Training


Upcoming Covidence Training for Dalhousie affiliates:

Have you got questions about how to use Covidence for your project or review? Then please join us for our upcoming training webinar for Dalhousie University users at 1:00 pm (ADT) on Tuesday, April 20th, 2021. Register through Covidence for this webinar here.

This session includes a live demo providing an overview of the systematic review workflow, and will cover the following topics:
1. What’s new in Extraction 2.0 and why we improved it
2. What study types, review types and quality assessment types are now supported
3. How to save time with the new template builder
4. Our top five tips to consider before and during your next data extraction

5. We’ll then aim to answer questions at the end, whether that’s about data extraction itself, or using Covidence to do it

This webinar is for researchers who have some familiarity with systematic/scoping reviews and Covidence. An introductory overview with more details will be offered during the Library Research Bootcamp later this spring.

Please be sure to register here if you'd like to join this webinar, or if you're unable to join but would like to receive a recording of the session ~24 hours after it commences.

What is a systematic review?

"A systematic review aims to comprehensively locate and synthesize research that bears on a particular question, using organized, transparent, and replicable procedures at each step in the process."

(Littell, Corcoran, & Pillai 2008) [1]


Introductory video from Yale University's informative video series on systematic reviews:


systematic review is a thorough compilation and analysis of all known evidence on a given subject. In order to be formally recognised by publishers and repositories, a systematic review must include the following elements:

  1. A clearly defined research question and protocol (research plan). The research question is often developed after performing preliminary research on the subject, ensuring that it is viable for a systematic review. You should also thoroughly search the literature to ensure no other systematic review already exists on your topic.
  2. Evidence of a rigorous search process. The reason why it is called a "systematic" review is because of the systematic search process that is required to uncover all of the evidence on a given subject. Systematic searching demands a carefully planned and thorough search strategy that will recall the maximum number of relevant results. For this reason, in addition to simply presenting search results, systematic reviews must include the exact search strategy used to find literature in each database.
  3. Inclusion and exclusion criteria. Not all evidence found during the search process will be relevant or appropriate for your research question. That is why it is important to clearly define the criteria you use to decide which studies should and should not be included in your analysis.
  4. Critical appraisal and bias assessment of all included studies. If a study is to be included in your review, the quality of its evidence must be critically appraised by each member of your research team. Additionally, because all studies carry an inherent risk of bias, studies should be thoroughly evaluated on their impartiality. This step ensures that your systematic review will represent the highest possible quality of evidence.
  5. An in-depth report outlining the process of finding and appraising literature, extracting data, measuring bias, and analysing results. Systematic review report guidelines can be found in many places, and are discussed in more detail here.


[1] Littell, J.H., Corcoran, J., & Pillai, V. (2008). Systematic Reviews and Meta-Analysis. Oxford University Press. Retrieved from

Systematic Reviews on the 6S Pyramid


Systematic reviews are an integral part of Evidence Based Practice. They are types of syntheses, which sit in the middle of the 6S Pyramid of filtered or pre-appraised evidence. The 6S Pyramid shows the hierarchy of the strongest types of medical evidence.

For more information on Evidence Based Practice, please visit the EBP section of the Medicine Subject Guide:

Library Services

The librarians at the Kellogg Library are eager to assist you with your systematic review needs. Please visit the "How can the library help you?" section of this guide for more information.

Before Getting Started

Plan ahead. Systematic reviews normally take over a year to complete; be sure to allow ample time to produce the highest quality report possible.

Assemble a team. Systematic reviews are never produced independently, but rely on a team of experts working together.

Brush up on your search skills. Be sure to familiarise yourself with advanced searching techniques, especially in the most common health sciences databases.

Know what's required. For the purpose of transparency and reproducibility - the tenets of good science - your systematic review should adhere to guidelines on standards. For more information about these guidelines, click here.


Training Opportunities