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Developing Your Research Question

Developing your research question is one of the most important steps in the research process. At this stage, you have often identified a knowledge gap in your field and are aiming to answer a specific question:

  • If X is prescribed, then Y will happen to patients?

OR assess an intervention:

  • How does X affect Y?

OR synthesize the existing evidence

  • What is the nature of X? 

Whatever your aim, formulating a clear, well-defined research question of appropriate scope is key to a successful evidence synthesis. The research question will be the foundation of your synthesis and from it, you will identify 2-5 possible search concepts. These search concepts will later be used to build your search strategy.


Formulating a research question takes time and your team may go through different versions until settling on the right research question. To help formulate your research question, some research question frameworks are listed below. Think of these frameworks as you would for a house or building. A framework is there to provide support and to be a scaffold for the rest of the structure. In the same way, a research question framework can also help structure your evidence synthesis question. 

PICO for Quantitative Studies

  • P       Population/Problem
  • I        Intervention/Exposure
  • C       Comparison
  • O      Outcome

Is gabapentin (intervention), compared to placebo (comparison), effective in decreasing pain symptoms (outcome) in middle aged male amputees suffering phantom limb pain (population)?

Inclusion & Exclusion Criteria

Inclusion and exclusion criteria are developed after a research question is finalized but before a search is carried out. They determine the limits for the evidence synthesis and are typically reported in the methods section of the publication. For unfamiliar or unclear concepts, a definition may be necessary to adequately describe the criterion for readers.

Inclusion/Exclusion Criteria


If there has been a previous review undertaken then it is not necessary to go back over ground covered in the earlier review. Instead refer to it and the findings from that study in the introduction.

Exposure of interest

The participants in the study may need to have experienced a particular condition to be considered for inclusion (e.g. received prenatal classes, given a particular drug, had a disease at a particular graded level or higher).

Geographic location of study

It may be necessary to limit the review to only studies targeting the same population group of interest for a broader original study or to countries which share similar demographic or economic factors with the target group.


It is usually not necessary to arrange translation of scientific works unless the review is attempting to come to a definite conclusion about a very specific clinical outcome which requires every applicable paper to be included.


Reviews may be restricted to only adult or child studies or to certain age groups. The Medline, Embase and Cinahl databases have age groups as subject headings for included articles.

Peer review

Sometimes reviews will exclude non-peer reviewed literature but gray literature such as technical reports and web-based guidelines may be important for certain research questions.

Reported outcomes

The inclusion of a study may depend on whether particular outcomes of interest have been reported and in an appropriate, consistent manner. The outcomes may be excluded if they are self-reported rather than using objective measures.


The study may be excluded or included based on where the participants were located (e.g. school, hospital, inpatient, community-based care).

Study design

The inclusion of only selected study designs is a way to make the review much more manageable and applicable to the research question. Study designs can include those in which participants were surveyed at one point in time (e.g. cross-sectional studies and ecological studies) and study designs that are conducted over time.

Type of publication

Systematic reviews usually search for original studies. Commonly excluded publications are reviews and editorials. Letters may also be excluded, however this should be done with caution as sometimes the letter format will be used to report small scale studies.