Background

In this first section, we will review some basic study design concepts that will help you better understand the purpose of propensity scores and why the methods for applying them may differ between protocols. These include the concepts of causality, the counterfactual, confounding, average treatment effect (ATE), and average treatment effect among the treated (ATT). If you are already familiar with these concepts, you may proceed to Section 1.

Are you familiar with the above concepts? (click on your choice)

• Yes, take me to section 1
• Yes, but I would like to review
• No