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Systematic reviews

A brief overview of systematic reviews and resources to support producing one.

Formulating a clear and concise question

“ A good systematic review is based on a well formulated, answerable question. The question guides the review by defining which studies will be included, what the search strategy.”

A systematic review questions needs to be

  • Clear
  • Focussed
  • Specific

To help formulate a focussed research question the PICO tool has been created. PICO is a mnemonic for Population, Intervention, Comparison and Outcome. These elements have been highlighted to help define the core elements of the question which will be used in the literature search.

The elements of PICO


Who or what is the topic of interest, in the health sciences this may be a disease or a condition, in the social sciences this maybe a social group with a particular need.


The intervention is the effect or the change upon the population in question. In the health sciences this could be a treatment, such as a drug, a procedure or a preventative activity. Depending on the discipline the intervention could be a social policy, education, ban, or legislation.


The comparison is a comparison to the intervention, so if it were a drug it may be a similar drug in which effectiveness is compared. Sometimes the comparator is a placebo or no comparison.


The outcomes in PICO represent the outcomes of interest for the research question. The outcome measures will vary according to the question, but will provide the data against which the interventions effectiveness is measured.

Not all systematic review questions are well served by the PICO mnemonic and a number of other models have been created, these include:  ECLIPSE (Wildridge & Bell, 2002), SPICE (Booth, 2004), and SPIDER (Cooke, Smith, & Booth, 2012).