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Systematic Reviews, Scoping Reviews, and other Knowledge Syntheses

Constructing a good research question

Formulating a well-constructed research question is essential for a successful review. You should have a draft research question before you choose the type of knowledge synthesis that you will conduct, as the type of answers you are looking for will help guide your choice of knowledge synthesis.


Examples of systematic review and scoping review questions

A systematic review question A scoping review question
Typically a focused research question with narrow parameters, and usually fits into the PICO question format Often a broad question that looks at answering larger, more complex, exploratory research questions and often does not fit into the PICO question format
Example: "In people with multiple sclerosis, what is the extent to which a walking intervention, compared to no intervention, improves self-report fatigue?" Example: "What rehabilitation interventions are used to reduce fatigue in adults with multiple sclerosis?"


Process of formulating a question

Developing a good research question is not a straightforward process and requires engaging with the literature as you refine and rework your idea.

Some questions that might be useful to ask yourself as you are drafting your question:

  • Does the question fit into the PICO question format?
  • Have you defined all of your terms? (Even if your question does not fit into a PICO, it can be helpful to think about whether you have defined your population, intervention, etc.)
    • What age group?
    • What type or types of conditions?
    • What intervention? How else might it be described?
    • What outcomes? How else might they be described?
    • What is the relationship between the different elements of your question?
  • Do you have several questions lumped into one? If so, should you split them into more than one review? Alternatively, do you have many questions that could be lumped into one review?

A good knowledge synthesis question will have the following qualities:

  • Be focused on a specific question with a meaningful answer
  • Retrieve a number of results that is manageable for the research team (is the number of results on your topic feasible for you to finish the review? Your initial literature searches should give you an idea, and a librarian can help you with understanding the size of your question).


Inclusion/Exclusion Criteria

Considering the inclusion and exclusion criteria

It is important to think about which studies will be included in your review when you are writing your research question. The Cochrane Handbook chapter (linked below) offers guidance on this aspect.

McKenzie, J. E., Brennan, S. E., Ryan, R. E., Thomson, H. J., Johnston, R. V, & Thomas, J. (2021). Chapter 3: Defining the criteria for including studies and how they will be grouped for the synthesis. Retrieved from

Has your review already been done?

Once you have a reasonably well defined research question, it is important to make sure your project has not already been recently and successfully undertaken. This means it is important to find out if there are other knowledge syntheses that have been published or that are in the process of being published on your topic.

If you are submitting your review or study for funding, for example, you may want to make a good case that your review or study is needed and not duplicating work that has already been successfully and recently completed—or that is in the process of being completed. It is also important to note that what is considered “recent” will depend on your discipline and the topic.

In the context of conducting a review, even if you do find one on your topic, it may be sufficiently out of date or you may find other defendable reasons to undertake a new or updated one. In addition, looking at other knowledge syntheses published around your topic may help you refocus your question or redirect your research toward other gaps in the literature.


Where to find other reviews or syntheses

The Cochrane Library (including systematic reviews of interventions, diagnostic studies, prognostic studies, and more) is an excellent place to start, even if Cochrane reviews are also indexed in MEDLINE/PubMed.

By default, the Cochrane Library will display “Cochrane Reviews” (Cochrane Database of Systematic Reviews, aka CDSR). You can ignore the results which show up in the Trials tab when looking for systematic reviews: They are records of controlled trials. 

The example shows the number of Cochrane Reviews with hiv AND circumcision in the title, abstract, or keywords.

Image showing results tabs in the Cochrane Library

Subject-specific databases you can search to find existing or in-process reviews

From additional limits, under EBM-Evidence Based Medicine, choose Systematic ReviewTo limit your search strategy to systematic reviews: Go to Additional Limits, and under EBM-Evidence Based Medicine, choose Systematic Review.

Alternatively, you can use a search hedge/filter; for example, the filter used by BMJ Best Practice to find systematic reviews in Embase (can be copied and pasted into the Embase search box then combined with the concepts of your research question):

(exp review/ or (literature adj3 review$).ti,ab. or exp meta analysis/ or exp "Systematic Review"/) and ((medline or medlars or embase or pubmed or cinahl or amed or psychlit or psyclit or psychinfo or psycinfo or scisearch or cochrane).ti,ab. or RETRACTED ARTICLE/) or (systematic$ adj2 (review$ or overview)).ti,ab. or (meta?anal$ or meta anal$ or meta-anal$ or metaanal$ or metanal$).ti,ab.

Alternative interface to PubMed: You can also search MEDLINE on the Ovid platform, which we recommend for systematic searching. Perform a sufficiently developed search strategy (be as broad in your search as is reasonably possible) and then, from Additional Limits, select the publication type Systematic Reviews, or select the subject subset Systematic Reviews Pre 2019 for more sensitive/less precise results. 

The subject subset for Systematic Reviews is based on the filter version used in PubMed.

Perform a sufficiently developed search strategy (be as broad in your search as is reasonably possible) and then, from Additional Limits, select, under Methodology, 0830 Systematic Review

Perform a sufficiently developed search strategy on MEDLINE via PubMed (be as broad in your search as is reasonable) and then use the “Article types” filter for “Systematic Reviews” to see if other reviews have been published on your topic. Systematic reviews found in PubMed and not published by collaborations like Cochrane, Campbell, BEME or JBI, for example, may require more careful critical appraisal for quality.

See Systematic Reviews Search Strategy Applied in PubMed for details.

References on question formulation frameworks

Munn Z, Stern C, Aromataris E, Lockwood C, Jordan Z. What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences. BMC Med Res Methodol. 2018;18(1):5. doi:10.1186/s12874-017-0468-4

Scoping reviews: Developing the title and question. In: Aromataris E, Munn Z (Editors). JBI Manual for Evidence Synthesis. JBI; 2020.

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Due to a large influx of requests, there may be an extended wait time for librarian support on knowledge syntheses.


Find a librarian in your subject area to help you with your knowledge synthesis project.


Or contact the librarians at the
Schulich Library of Physical Sciences, Life Sciences, and Engineering

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