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[Application of propensity score matching in the design of an epidemiological study].

INTRODUCTION
In this article, we presented the rationale and calculation procedures of the propensity score matching (PSM), and its application in the designing stage of an epidemiological study. Based on existing observational data, PSM can be used to select one or more comparable controls for each subject in 'treatment' group according to the propensity scores estimated by 'treatment' variable and main covariates. The results of an example analysis showed that the bias for main confounders between the treated and control samples declined more than 55% after PMS.


CONCLUSION
PSM can reduce most of the confounding bias of the observational study, and can obtain approximate study effect to the randomized controlled trials when used in the designing of the epidemiological study.