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Step 2: PICO

A common way to get started looking for research articles is by using the PICO method.  PICO includes the following elements:

P Population
I Intervention or treatment
C Comparison
O Outcome



Populations can have many different components.  Typically, a population is made up of at least one identity category combined with another factor.  Other factors could be diagnoses, care settings, or something else.  

Below are some examples of each that can help you define your population.  





Adults, Teens, Infants, Children, Seniors, etc.


African American, Hispanic, Caucasian, etc.


Salvadorean, Chinese, Filipino, Egyptian, etc.


English, Spanish, Chinese, HIndi. etc.


Catholic, Muslim, Jewish, Buddhist, etc.



Care Circumstances



Fever, breast cancer, laryngitis, hip fractures, etc.

Insurance categories

Medicare, Medicaid, etc.

Care location

Hospital, in-home care, hospice, etc.




Interventions are used in response to a particular diagnosis or problem faced by a patient population.  The goal of health research is to measure and improve the effectiveness of particular interventions or treatments on that population.  

When selecting your intervention (I) in your PICO, choose only one intervention to examine, and make sure to choose an appropriate intervention for the population (and diagnosis).  

A good way to start is by looking up the diagnosis in a reference source to learn about common interventions.  The sources below have excellent articles on many diagnoses:



The C in PICO means an alternative to the intervention (I) that you are trying to measure.  An alternative could be another intervention, but it's most commonly no intervention at all.  So if the intervention you are measuring is chemotherapy, you can compare its effectiveness to no chemotherapy.  Then you can measure which one creates a better outcome for your population.



The outcome in your PICO is the intended effect of the intervention.  Remember, you don't know the effect of a particular intervention on a patient population until you do your research.  So the (O) in PICO is an outcome you want to find or a likely outcome you think you might find.