Paper 165-29 1 Performing a 1:N Case-Control Match on Propensity Score Lori S. Parsons, Ovation Research Group, Seattle, Washington ABSTRACT A case-control matched analysis is often used in observational studies to reduce selection bias and approximate a randomized trial. A propensity score is the predicted probability of an outcome. It has been shown that a sample matched on propensity score will be similar for all the covariates that went into computing the propensity score. Thus, matching on the propensity score can reduce the selection bias in an observational study. This paper presents a macro that performs a 1:N case-control match on the propensity score; the analyst is allowed to specify the number of controls to match to each case. The macro makes "best"

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