Statistics and Data Science Seminar
Professor Ajit C. Tamhane
Northwestern University
Tree-Structured Gatekeeping Procedures
Abstract: This talk is in two parts. Part I will give a brief introduction to multiple
comparison procedures to provide the necessary background for Part II which is
the main topic. For brevity and simplicity, we shall restrict to procedures
based on p-values only.
Parallel and serial gatekeeping procedures have been recently proposed (Westfall
and Krishen 2001, and Dmitrienko, Offen and Westfall 2003) for testing
hierarchically ordered families of hypotheses. We generalize these procedures to
what we call tree-structured gatekeeping procedures. This generalization is
necessary to deal with problems involving hierarchically ordered multiple
objectives subject to logical restrictions, e.g., in the analysis of multiple
endpoints in dose-control studies and in superiority-equivalence testing. The
proposed approach is based on the closure principle of Marcus, Peritz and
Gabriel (1976) and uses weighted Bonferroni tests for intersection hypotheses.
In special cases of parallel or serial tree structures the closed testing
procedure can be shown to be equivalent to stepwise procedures, which are easy
to implement. Two illustrative clinical trial examples are given.
Note: This work is joint with Alex Dmitrienko, Brian Wiens and Xin Wang, and is
based on a paper that has recently appeared in Statistics in Medicine.
Friday April 20, 2007 at 2:00 PM in SEO 512