What best defines a propensity score?

• A. A method for randomizing treatment assignment
• B. A measure to estimate treatment effect when random assignment is not feasible
• C. A statistical technique to adjust for demographic differences
• D. A tool for predicting patient outcomes

Answer: (B)

A propensity score is best defined as a measure used to estimate treatment effects when random assignment to treatment groups is not practical or feasible. It is particularly useful in observational studies where treatment groups may differ in baseline characteristics, potentially leading to biased estimates of treatment effects. The propensity score helps to balance these differences by creating a score that reflects the likelihood of a participant receiving a particular treatment based on observed covariates. By matching or stratifying individuals with similar propensity scores, researchers can mimic some of the conditions of a randomized controlled trial, allowing for a more accurate assessment of treatment effectiveness in the presence of confounding variables. This approach enhances the validity of the findings by reducing selection bias in the estimation of treatment outcomes.