ABSTRACT
The purpose of this paper was to introduce the methods of the "layered person-time data" rate ratio analysis and the SAS implementation. The specific contents included the following four aspects： ① the point estimation and the confidence interval estimation of the layer i rate ratio in the stratified person-time data； ② the homogeneity test of the rate ratios among the different layers； ③ the point estimation and the confidence interval estimation of the common rate ratio； ④ the linear trend test of the incidence density in the stratified person-time data. Through two examples， it showed the statistical calculation process based on the SAS software to realize the aforementioned four kinds of the analysis contents， including providing the SAS program code， the explanation of the SAS output results， and giving the statistical and professional conclusions.