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Systematic Reviews - Research Guide

Using PICO or PICo

Why Use PICO?

PICO is a useful tool for asking focused clinical questions.

Slightly different versions of this concept are used to search for quantitative and qualitative reviews, examples are given below.

PICO for Quantitative Studies


Population or Problem Intervention or Exposure Comparison Outcome

What are the characteristics of the Population or patient?

What is the Problem, condition or disease you are interested in?

How do you wish to Intervene - what do you want to do with this patient - treat, diagnose, observe, etc.? What is the Comparison or alternative to the intervention - placebo, different drug or therapy, surgery, etc.? What are the possible Outcomes - morbidity, death, complications, etc.?



Here is an example of a clinical question that outlines the PICO components:

To develop an effective search strategy, use the PICO worksheet below.

This includes identifying:

  • Type of study
  • Limitations
  • Keywords or synonyms
  • Which database/s to search

For an example, see the completed worksheet.

PICO for Evidence-Based Veterinary Medicine

Evidence-Based Veterinary Medicine Toolkit 

Use the EBVM Toolkit to guide you through the steps:

  1. Asking an answerable clinical question

    • applying the PICO method

  2. Finding the best available evidence to answer the question

    • identifying search words, synonyms, and developing a search strategy

  3. Critically appraising the evidence for validity

    • determining levels of evidence

    • identifying type of study design

Use the Systematic Review Checklist and critical appraisal checklists to further develop your review.

PICo for Qualitative Studies


P I Co
Population or Problem Interest Context

What are the characteristics of the Population or the patient?

What is the Problem, condition or disease you are interested in?

Interest relates to a defined event, activity, experience or process Context is the setting or distinct characteristics


Here is an example of a clinical question that outlines the PICo components:

See the completed example worksheet below.

SPICE or SPIDER for Qualitative or Quantitative Studies

Two other mnemonics may also be used to create protocols for both qualitative and quantitative studies - SPIDER and SPICE.

SPIDER can be used for both qualitative and quantitative studies:


Sample Phenomenon of Interest Design Evaluation Research Type

Sample size may very in qualitative and quantitative studies

Phenomena of Interest include behaviours, experiences and interventions Design influences the strength of the study analysis and findings Evaluation outcomes may include more subjective outcomes - such as views, attitudes, etc. Research types include qualitative, quantitative or mixed method studies


Within social sciences research, SPICE may be more appropriate for formulating research questions:


Setting Perspective Intervention Comparison Evaluation

Setting is the context for the question - where

Perspective is the users, potential users, or stakeholders of the service - for whom Intervention is the action taken for the users, potential users, or stakeholders - what Comparison is the alternative actions or outcomes - what else Evaluation is the result or measurement that will determine the success of the intervention - what result or how well