This graphic ranks different types of publications and research activities according to their basis in evidence, with systematic reviews considered the strongest form of evidence-based literature.
Source: SUNY Downstate/Medical Research Library of Brooklyn, http://library.downstate.edu/EBM2/2100.htm
P: "Patient," "Population," or "Problem" (medical condition/disorder plus age, gender, ethnicity, or other characteristics)
I: "Intervention" or "Indicator" (treatment, therapy, diagnostic test)
C: "Comparison" or benchmark (an alternative intervention, a placebo, or absence of disease)
O: "Outcome" or anticipated result of intervention (what it will affect)
T: "Time" (the time it takes the intervention to achieve an outcome)
The PICO(T) format can help you develop a clear, answerable research question and decide what type of evidence you are looking for. The templates below can help you form a research question (note that not every question may contain all PICO(T) elements).
Some sample PICO templates:
For an intervention or therapy:
In _______(P), what is the effect of _______(I) on ______(O) compared with _______(C), within ________ (T)?
For a diagnosis or diagnostic test:
Are (is) _________ (I) more accurate in diagnosing ________ (P) compared with ______ (C) for _______ (O)?
For prevention questions:
For ________ (P) does the use of ______ (I) reduce the future risk of ________ (O) compared with _________ (C)?
Based on Melnyk B., & Fineout-Overholt E. (2010). Evidence-based practice in nursing & healthcare. New York: Lippincott Williams & Wilkins.