Arnold School of Public Health
Division of Biostatistics

 Lecture Presented By
Wenbin Lu, PhD
Statistics Department
North Carolina State University

“Change-Plane Analysis for Subgroup Detection and Sample Size Calculation”
Monday, March 26, 2018
1:00 – 2:00
Discovery I Building
Room 331

Abstract: In this work, we propose a systematic method for testing and identifying a subgroup with an enhanced treatment effect. We adopt a change-plane technique to first test the existence of a subgroup, and then identify the subgroup if the null hypothesis on non-existence of such a subgroup is rejected. A semiparametric model is considered for the response with an unspecified baseline function and an interaction between a subgroup indicator and treatment. A doubly-robust test statistic is constructed based on this model, and asymptotic distributions of the test statistic under both null and local alternative hypotheses are derived. Moreover, a sample size calculation method for subgroup detection is developed based on the proposed statistic. The proposed method is also extended to censored survival data. The finite sample performance of the proposed test is evaluated via simulations. Finally, the proposed methods for subgroup identification and sample size calculation are applied to a data from an AIDS study.