A test for the existence of a subgroup with enhanced treatment effect and estimation of the subgroup if it exists. In addition, a sample size calculation procedure for this subgroup detection test.
subgroup_detect: test for the existence of a subgroup and estimation of the subgroup.
sample_size:estimate of the required sample size for subgroup detection test.
Ailin Fan, Rui Song, and Wenbin Lu, (2016). Change-plane analysis for subgroup detection and sample size calculation, Journal of the American Statistical Association, in press.