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Evidence-Based Research: Phrasing Research Questions

The researchable question

The first step in doing evidence-based practice research is forming a researchable question. Questions that are too broad or too narrow can make your research difficult, if not impossible.

Clinical example:

  • Too broad: How do you control infection?
    • This topic is so broad that you'd have difficulty wading through all of the results.
  • Too narrow: At the Johns Hopkins Neonatal Intensive Care Unit, what is the best way to control infection among Asian American babies born at 32 weeks? 
    • This question is so specific that there probably hasn't been anything published on that specific location regarding that specific population.
  • Just right: In the NICU, what is the effect of hand washing on infection control compared with hand sanitizers, over 6 months?

Non-clinical example:

  • Too broad: Is heart disease experienced evenly by race?
    • This topic is so broad that you'd have difficulty wading through all of the results.  Also the wording in the question has to be more specific (use synonyms to include all possible versions).  For instance, heart disease is better known in the literature as cardiovascular disease, so search both ways. 
  • Too narrow: At the Johns Hopkins Intensive Care Unit, is the cardiovascular mortality rate in January different by race? 
    • This question is so specific that there probably hasn't been anything published on that specific location regarding that specific population. It can be only be determined by accessing the electronic medical records in the hospital and finding the rate.
  • Just right: What is the impact of race (Black Americans versus White Americans) on long-term cardiovascular mortality after controlling for age and income in United States adults? 
    • This question is just right because the variable name like “cardiovascular mortality” are descriptive and reflective of what is found in the literature.  Additionally, there are some control variables included to make sure that even if each group of race had individuals with different ages or different incomes, this would not explain away the differences in cardiovascular mortality impacted by race.

PICOT and other models

PICOT is a mnemonic that helps you remember the key components of a well-focused question. It stands for:

  • P = Patient, Population or Problem
  • I = Intervention, Prognostic Factor, or Exposure
  • C = Comparison (optional)
  • O = Outcome
  • T = Time

PICOT examples:


In _______(P), what is the effect of _______(I) on ______(O) compared with _______(C) within ________ (T)? 

In the aged population, what is the effect of exercise programs on accidental falls, as compared with no exercise?


Are ____ (P) who have _______ (I) at ___ (Increased/decreased) risk for/of_______ (O) compared with ______ (P) with/without ______ (C) over _____ (T)?

Are adult smokers with a history of childhood asthma at increased risk of COPD compared to adult smokers with no history of asthma?

Diagnosis or diagnostic test

Are (is) _________ (I) more accurate in diagnosing ________ (P) compared with ______ (C) for _______ (O)? 

Is the Hemoglobin A1C test more accurate in diagnosing diabetes as compared with fasting blood sugar levels?


For ________ (P) does the use of ______ (I) reduce the future risk of ________ (O) compared with _________ (C)? 

For people with type 2 diabetes, does zinc supplementation reduce the future risk of foot ulcers compared with placebo?


Does __________ (I) influence ________ (O) in patients who have _______ (P) over ______ (T)? 

In adults with osteoarthritis, does low vitamin D levels in the bloodstream predict the rate of future hip fractures?


How do ________ (P) diagnosed with _______ (I) perceive ______ (O) during _____ (T)? 

How do cancer patients diagnosed with alopecia perceive their self-esteem during and after chemotherapy?


Public Health:

PICO(T) is commonly used to formulate research questions, sometimes referred to as ‘PI/ECO’ (Population/participants, Intervention/Exposure, Comparison, Outcome). The PI/ECO structure can be readily amended for different question types (NHMRC Guidelines, 2019). A simple example might be: 

  • Population / participants: Non-institutionalized civilian residents of the United States 
  • Intervention (or Exposure): Hypertension (or Low Socioeconomic Status)
  • Comparison: Respondents without hypertension 
  • Outcomes: Cardiovascular disease or cardiovascular mortality 
  • Types of studies: Cross-sectional, Longitudinal

Alternate Models:

  • PECO – Population | Environment | Comparison | Outcome
    Very similar to PICO but looking at the effect of exposure to something e.g. smoky atmosphere
  • SPICE - Setting | Population | Intervention | Comparison | Evaluation
    Another variant of PICO but this time including the setting (where? in what context?)
  • CIMO - Context | Intervention | Mechanisms | Outcome
    A variant of PICO suitable for management and organization studies
    • ECLIPSE - Expectation | Client group | Location | Impact | Professionals | Service
      Recommended for health policy/management searches
  • SPIDER – Sample | Phenomenon of Interest | Design | Evaluation | Research Type
    Developed to create effective search strategies of qualitative and mixed-methods research - more specific than PICO/PECO

Search terms

Once you've developed your question, it's time to find keywords or search terms that you can use in the Library databases to find articles relevant to your question. Remember that each article does not necessarily need to address ALL the aspects of your question.

To learn more about selecting and combining appropriate search terms, please see our guides: