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Literature Searching: Advanced Searching: PICO

Follow our step-by-step guide to help you carry out a good literature search

Develop your research question and search strategy

Sometimes it helps to write an answerable question that begins and ends with a patient, population, or problem. This helps to develop a clinical research and/or EBP question. Using PICO or PEO  for developing searchable and answerable clinical questions are useful tools during the research process.

What is PICO?

PICO is most widely used in quantitative research questions:



Try using  the PICO search option in TRIP  for systematic reviews, meta analyses etc.



Is Chemotherapy (intervention) more efficient than Surgery (comparison) in managing stage 1 breast cancer (problem) for women patients (population)?

*Note: It is not necessary to use every element in PICO or to have both a problem and population in your question. PICO is a tool that helps researchers frame an answerable EBP question. 

Other Models

The FINER and SPIDER models can be useful for qualitative, quantitative and mixed methodology:

For more information, have a look at these articles:

Beyond PICO: The SPIDER Tool for Qualitative Evidence Synthesis

(for off campus access, click on institutional login, then UK, university of dundee & then your own username and password)

Formulating a researchable question: A critical step for facilitating good clinical research

What is PEO?

PEO is most useful for qualitative research questions:




Does the quality of life (outcome or theme) change when women on HRT (population and problems) are diagnosed with breast cancer (exposure)?

Other techniques - beyond Boolean

Once you master using Boolean techniques for searching, there are a few more advanced searches you can achieve:


Nested searches are a more complex boolean search e.g. 

cancer NOT (breast OR bowel) AND treatment

This search would look for the treatment of all cancer except breast or bowel.


Some databases allow for searching for words within the same sentence or within a defined number of words within one another.

"breast cancer" SAME "treatment outcomes" : using SAME will search for "breast cancer" and "treatment outcomes" in same sentence

"breast cancer" W3 "treatment outcomes" : using W3 will search for "breast cancer" within 3 words of "treatment outcomes"

"breast cancer" NEAR  "treatment outcomes" : using NEAR will search for "breast cancer" within the databases definition of NEAR to "treatment outcomes"