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Systematic Reviews

A guide directing researchers on the systematic review process. Layout based on Doing a Systematic Review: A Student's Guide, 2nd Edition, by Angela Boland, M. Gemma Cherry, and Rumona Dickson.

Developing A Research Question

There are several different methods researchers might use in developing a research question. The best method to use depends on the discipline and nature of the research you hope to review. Consider the following example question templates.


Using PICO can help you define and narrow your research question so that it is specific.

  • P  - Patient, population, or problem
  • I   - Intervention
  • C - Comparison or Control
  • O - Outcome

Think about whether your question is relevant to practitioners, and whether the answer will help people (doctors, patients, nurses) make better informed health care decisions.

You can find out more about properly formulated questions by reviewing the YouTube video below.

Variations to PICO

The PICO method is used frequently, though there are some variations that exist to add other specifications to studies collected. Some variations include PICOSS, PICOT, and PICOC.

  • PICOSS (Boland, Cherry, & Dickson, 2017)
    • In addition to the fundamental components of PICO, additional criteria are made for study design (S) and setting (S).
    • (T), in this instance, represents timeframe. This method could be used to narrow down length of treatment or intervention in health research.
  • PICo
    • In research where there may not be a comparison, Co instead denotes the context of the population and intervention being studied.


Using SPIDER can help you define and narrow your research question so that it is specific. This is typically used in qualitative research (Cooke, Smith, & Booth, 2012).

  • S - Sample
  • PI - Phenomenon of Interest 
  • D - Design
  • E - Evaluation
  • R - Research type


Yet another search measure relating to Evidence-Based Practice (EBP) is SPICE. This framework builds on PICO by considering two additional axes: perspective and setting (Booth, 2006).

  • S - Setting
  • P - Perspective
  • I - Intervention
  • C - Comparison
  • E - Evaluation

Inclusion and Exclusion Criteria

Setting inclusion and exclusion criteria is a critical step in the systematic review process.

  • Inclusion criteria determine what characteristics are needed for a study to be included in a systematic review.
  • Exclusion criteria denote what attributes disqualify a study from consideration in a systematic review.
  • Knowing what to exclude or include helps speed up the review process.

These criteria will be used at different parts of the review process, including in search statements and the screening process.


Has this review been done?

After developing the research question, it is necessary to confirm that the review has not previously been conducted (or is currently in progress).

Make sure to check for both published reviews and registered protocols (to see if the review is in progress). Do a thorough search of appropriate databases; if additional help is needed, consult a librarian for suggestions.