What do inclusion and exclusion criteria specify?

• A. Criteria that determine who may participate (inclusion) and who may not (exclusion).
• B. The budget and funding eligibility for trial sites.
• C. The duration of the trial.
• D. The method of statistical analysis.

Answer: (A)

Inclusion and exclusion criteria define who may participate in a trial by listing the conditions participants must meet to enroll (inclusion) and those that would disqualify someone from participating (exclusion). This screening framework shapes the study population to protect participant safety and to make the results interpretable by reducing variability that could obscure the treatment effect. Think of it as setting the boundaries for who the study is meant to learn about, ensuring participants truly reflect the target group and that the data gathered are reliable. Common elements include age range, confirmed diagnosis, disease severity, prior treatments, organ function, pregnancy status, ability to adhere to the protocol, and informed consent capacity. These criteria are about who can participate, not about how the trial is funded, how long it runs, or how the data will be analyzed.