A test against the stratified additive hazards model

Stratified data are commonly encountered in practice. An interesting problem for this type of data is to test the existence of stratum effect. This paper discusses hypothesis testing of stratum effect for interval-censored data with informative observation times under the stratified additive hazards model. We construct a test statistic for this test problem, and show that the test statistic is asymptotically distributed as a chi-squared distribution. Finite sample performance of the proposed method is assessed through an extensive simulation study, which indicates the procedure works well. A real data set from a hemophilia study is analyzed to illustrate the proposed method.