Abstract #300697

This is the preliminary program for the 2003 Joint Statistical Meetings in San Francisco, California. Currently included in this program is the "technical" program, schedule of invited, topic contributed, regular contributed and poster sessions; Continuing Education courses (August 2-5, 2003); and Committee and Business Meetings. This on-line program will be updated frequently to reflect the most current revisions.

To View the Program:
You may choose to view all activities of the program or just parts of it at any one time. All activities are arranged by date and time.

The views expressed here are those of the individual authors
and not necessarily those of the ASA or its board, officers, or staff.

Back to main JSM 2003 Program page
JSM 2003 Abstract #300697
Activity Number: 180
Type: Contributed
Date/Time: Monday, August 4, 2003 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract - #300697
Title: Cox Proportional Hazards Analyses with Small Centers
Author(s): Fraser B. Smith*+ and Hong Laura Lu
Companies: Food and Drug Administration and Food and Drug Administration
Address: PO Box 10643, Gaithersburg, MD, 20898-0643,
Keywords: Cox proportional hazards ; stratification ; small centers
Abstract:

In randomized, double-blind, multicenter, clinical trials there is frequently a discussion about whether or not one should stratify by center when using a Cox proportional hazards regression analysis. When there are small centers how small do they have to be before they present a problem and when is it necessary to pool them? Is it sufficient to have at least one failure per center in each treatment group? Or is it sufficient to have at least one failure per treatment group? Examples will be used to illustrate what can happen when there are rare events and a large number of small centers. Stratified and unstratified Cochran-Mantel Haenszel and logit chi-square tests will be compared to those obtained using Monte Carlo estimates and Cox proportional hazards regression analyses. The results of these analyses suggest that it may only be necessary to have at least one patient per treatment group in most centers. Therefore stratified analyses are most likely be problematic when there are very small strata (e.g., race) or subset analyses (e.g., restricted to patients who remain on treatment for the duration of the study).

  • The address information is for the authors that have a + after their name.
  • Authors who are presenting talks have a * after their name.

Back to the full JSM 2003 program

JSM 2003 For information, contact meetings@amstat.org or phone (703) 684-1221. If you have questions about the Continuing Education program, please contact the Education Department.
Revised March 2003