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Evidence Based Practice: Type of Question & Type of Study

An Interprofessional Guide

What Type of Question are You Asking?

After you have crafted your question using the PICO format, another step in the process to to identify the type of question you are asking, and identify the optimal type of research design to answer your question. 

Type of Question

Are you asking a question related to a diagnosis? There are four primary question types:

  1. Therapy: Does the treatment work? How effective is the intervention?
  2. Diagnosis / Diagnostic Test: What is the ability of the test to predict the likelihood of a disease?
  3. Prognosis: What is the future course of the patient?
  4. Harm/Etiology: What is the cause of the problem? What is the harmful effect of an intervention or exposure?

What Type of Study do you Need?

Type of Study

After you choose your question type, now its time to identity the research design. There are different types of research studies you can locate in the primary literature, and different research designs are better suited to answering different types of clinical questions.

The strength of the evidence increases the higher you are on the hierarchy.  Your risk of bias increases and the strength of evidence decreases the lower you are on the hierarchy.

EBM Levels of Evidence Pyramid

Dahlgren Memorial Library. Evidence-based medicine resource guide: Clinical questions, PICO, & study designs. Updated 2016. Accessed June 24, 2016.

Your mnemonic now reads:

  • P  =Patient (population or problem)
  • I = Intervention (prognostic factor or exposure)
  • C = Comparison
  • O = Outcome
  • T = Type of Question
  • T = Type of Study