Estimating the treatment effect between a treatment group and a control group in an observational study is a challenging problem in statistics. Without random assignment of subjects, there are likely to be differences between the treatment group and control group on a set of baseline covariates. If one of these baseline covariates is correlated to the response variable, then the difference in sample means between the groups is likely to be a biased estimate of the true treatment effect.;Propensity score matching has become an increasingly popular strategy for reducing bias in estimates of the treatment effect. This reduction in bias is accomplished by identifying a subset of the original control group, which is similar to the treatment group in terms of the measured baseline covariates.;Our research focused on the development of a new procedure that combines propensity score matching and a rank-based analysis of the general linear model. Our procedure was compared to several others in a Monte Carlo simulation study. Overall, our procedure produced highly efficient and robust confidence intervals for a treatment effect in an observational study. In addition to the Monte Carlo simulation study, our procedure and several other propensity score matching techniques were used to analyze two real world datasets for the presence of a treatment effect.
展开▼
