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Systematic Reviews and other Knowledge Synthesis: Formulate question

This guide covers the basics of conducting a systematic review and other types of knowledge synthesis

Formulate question

The systematic review pulls together studies that answer the same question; thus, it is very important to carefully consider your research question.


  1. Put your question in the PICO format to make it searchable. Click here for a refresher.
  2. Conduct a preliminary search to make sure a systematic review doesn't already exist on your topic


A research question should be: Characteristics of a good research question:
  • clear
  • focused
  • well-formulated
  • answerable
  • defined at the beginning of your systematic review.


A well-formulated question is one of the keys to a successful review and will assist with:

  • determining inclusion and exclusion criteria &
  • creating a search strategy.

Hulley, S. B., Cummings, S. R., & Browner, W. S. (2013). Designing clinical research.

PICO - used in evidence-based clinical practice; quantitative reviews

Additional letters (for PICOT, PICOS, PICOTS, PICOTTS)

  • Timeframe
  • Type of study
  • Setting

Haynes, R. B., Richardson, W. S., Rosenberg, W., & Sackett, D. L. (1997). Evidence based medicine: How to practice and teach EBM. New York: Churchill Livingstone.

SPICE- useful for qualitative research

Booth, A. (2006). Clear and present questions formulating questions for evidence based practiceLibrary Hi Tech24(3), 355–368.

Further Reading

Methley, A. M., Campbell, S., Chew-Graham, C., McNally, R., & Cheraghi-Sohi, S. (2014). PICO, PICOS and SPIDER: A comparison study of specificity and sensitivity in three search tools for qualitative systematic reviews. BMC Health Services Research, 14(1), 579.


PEO - useful for qualitative research questions

Moola, S., Munn, Z., Sears, K., Sfetcu, R., Currie, M., Lisy, K., Tufanaru, C., Qureshi, R., Mattis, P., Mu, P. & (2015). Conducting systematic reviews of association (etiology). International Journal of Evidence-Based Healthcare, 13 (3), 163-169.

SPIDER - useful for qualitative & mixed-methods research

Cooke, A., Smith, D., & Booth, A. (2012). Beyond PICO: the SPIDER tool for qualitative evidence synthesisQualitative health research22(10), 1435–1443.

PerSPECTiF - useful for qualitative research

Booth, A., Noyes, J., Flemming, K., Moore, G., Tunçalp, Ö., & Shakibazadeh, E. (2019). Formulating questions to explore complex interventions within qualitative evidence synthesisBMJ global health4(Suppl 1), e001107.

Preliminary searching

It is important to make sure a review has not already been done on the topic. You should conduct a literature search for other knowledge synthesis that have been done in that area or are in the process of being published. There may be older reviews on your topic that are out of date, justifying the need for a new review or knowledge synthesis. 


Where to look for systematic reviews:

Best Evidence Medical Education Collaboration (BEME)

Campbell Collaboration

Cochrane Library


Google Scholar