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Public Health

Guide to library research for evidence-informed public health practice.


Whether you are practicing evidence-informed decision making or conducting research (e.g. a systematic review), the first step of the process is to clearly define the question or problem in a searchable and answerable format. This step of the process helps you answer the questions:  

  • “Who is my target group?
  • What is the issue we are dealing with?
  • What specifically are we trying to change?”

Source: NCCMT.

Identifying Key Concepts and Search Terms

Using a framework to develop your question can help to identify the main concepts of your review topic (see further down the page). Whether you use a framework or not, the goal is to identify the main concepts of your question and the synonyms / similar terms that might be used to describe each of those concepts:

Image from UCSF Library: 

Combining search terms with AND or OR:

  • Use AND to combine different main concepts of your search: childhood AND obesity. Narrows results
  • Use OR to include similar terms / synonyms (and sometimes antonyms) for a concept: childhood OR adolescence. Fertility OR infertility. Broadens results

Considerations for searching:

It is not always necessary to include all of your main concepts in the search. In some PICO questions, the outcome (O) is implied and does not need to be included. In other cases, any and all outcomes might of interest and so the search strategy can leave this out to keep it open.

Example for the research question: In seniors with dementia, does a falls prevention program, compared to no falls prevention program, result in decreased falls?

  • In the following PICO question, the comparator (C) can be left out of the search strategy as there is no great way to search for "not" having the intervention (in contrast to when there is a placebo or an alternate intervention as a comparison)
  • Also, the intervention (I) somewhat implies the outcome (O), so the outcome (decreased falls) can be left out of the search strategy
  • The main concepts that should be included in this particular search are: seniors (P1), dementia (P2), and falls prevention (I). Keep in mind though that there are different ways of describing these three concepts and so synonyms / similar terms are important to include in the search as well

Frameworks for Question Formulation

Applying a framework when developing a question can help to identify the key concepts and determine inclusion and exclusion criteria.

PICo: Population/Participants, phenomenon of Interest, Context


Patient/Problem, Intervention, Comparison, Outcome, (Study design)


Patient/Problem, Exposure, Comparison, Outcome, (Study design)


Person, Environment, Stakeholders, Intervention, Comparison, Outcome


Population, Interventions, Professionals/Patients, Outcome, Healthcare Setting

PS: Population, Situation
SPICE: Setting, Perspectives, Intervention, Comparison, Evaluation


Example: PICO Question

P (Patient, Population, Problem) I (Intervention) C (Comparison) O (Outcome)
How would I describe a group of patients similar to mine?  What main interventions, prognostic factors or exposure are you considering? What is the main alternative to compare with the intervention?  What can you hope to accomplish, measure, improve or effect?


Otherwise healthy children…


exposure to in utero cocaine… 


children not exposed to in utero cocaine…

Result in:

increased risk of learning disabilities? 


Primary school children


school-based physical activity


no school-based physical activity

Result in:

a decrease in obesity

Example: SPICE Question

S (Setting) P (Perspective) I (Intervention) C (Comparison) E (Evaluation)
Where? For whom? What? Compared with what? With what result?
In the setting of rural communities From the perspective of a pregnant woman How does facility-based care Compare with traditional birth attendants at home In relation to the woman’s perceptions and experiences?

Example from: Booth, A., Noyes, J., Flemming, K., Moore, G., Tunçalp, Ö., & Shakibazadeh, E. (2019). Formulating questions to explore complex interventions within qualitative evidence synthesis. BMJ Global Health, 4(Suppl 1), e001107.