Western Libraries

Systematic & Scoping Reviews

Defining Your Research Question

Before embarking on your systematic search, you'll want to define your research topic in an easily searchable way. This involves separating out the key concepts of your research question. There are various tools to help you do this. One of the most commonly used is PICO (pictured below). These worksheets can help you formulate a searchable question.

PICO Model for Health Related Questions

  • Patient, Population, or Problem
  • Intervention
  • Comparison or Control (if appropriate)
  • Outcome

The PICO model is used for quantitative research and can also be utilized for qualitative research.

Alternate Models to Construct your Question

You can also use alternate models such as ECLIPSE or SPICE to construct your question.


  • Expectations (about improvement or innovation or information)
  • Client Group (at whom is the service aimed? e.g. persons above 65)
  • Location (where is the service sited? e.g. primary care, hospital)
  • Impact (what is the change in the service which is being looked for? What would constitute success? How is this being measured? –similar to outcomes in the PICO-format)
  • Professionals Involved
  • Service (e.g. outpatient services)

Van de Voorde, C. & Léonard, C. (2007). Search for Evidence and Critical Appraisal: Health Services Research (HSR). Belgian Health Care Knowledge Centre http://www.kce.fgov.be/index_en.aspx?SGREF=5211ECLIPSE


Setting (What is the context of the question?)

  • Perspective (Who are the users/potential users of the outcomes?)
  • Intervention (What is being done to them?)
  • Comparison (What are the alternatives?)
  • Evaluation (How will you measure if the intervention is successful?)

Van de Voorde, C. & Léonard, C. (2007). Search for Evidence and Critical Appraisal: Health Services Research (HSR). Belgian Health Care Knowledge Centre http://www.kce.fgov.be/index_en.aspx?SGREF=5211

Levels of Evidence

Levels of Evidence pyramid

Image credit: Adapted by Charlotte Beck and Suzan Zagar, UBC Library from the EBM Generator. 2012. Levels of Evidence Pyramid.

The Levels of Evidence can be visualized in a pyramid structure. This pyramid is organized into information that is searchable through individual databases, which is broken down into filtered information and unfiltered information, and information that is not searchable via individual databases. The pyramid can be broken down as follows, beginning at the top of the pyramid going down:

Searchable via Individual Databases:

  1. Filtered Information
    1. MetaAnalyses
    2. Systematic Reviews
    3. Critically Appraised Topics
    4. Critically Appraised Individual Articles
  2. Unfiltered Information
    1. Cohort Studies
    2. Case-controlled Studies, Case Series/Reports

Not searchable through individual databases: Background information / Expert Opinion

When considering what type of studies to include in your systematic review, think about the evidence pyramid above. Higher quality studies near the top of the pyramid are considered the best source of evidence.