JSM 2012 Home

JSM 2012 Online Program

The views expressed here are those of the individual authors and not necessarily those of the JSM sponsors, their officers, or their staff.

Online Program Home

Abstract Details

Activity Number: 35
Type: Contributed
Date/Time: Sunday, July 29, 2012 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract - #306123
Title: Impact of Stratified Randomization on Estimating Treatment Effect in ANCOVA Models
Author(s): Peter G Mesenbrink*+ and Jeff Maca
Companies: Novartis and Novartis
Address: One Health Plaza, East Hanover, NJ, , USA
Keywords: stratification ; randomization ; statistical power ; ANCOVA

A common consideration when designing a clinical trial is to stratify over known factors. These factors are chosen because they are believed to have a strong effect on the primary efficacy outcomes. These factors are incorporated over the concern that without inclusion the treatment groups would be unbalanced and lead to loss in study efficiency or power. We will examine different numbers of stratification factors and different magnitudes of effect for the stratification factors relative to the magnitude of the treatment effect in an ANCOVA model. In simulation studies conducted, even when the magnitude of the effect of the stratification factor is equal to or greater than the treatment effect, the loss of power is minimal even for small sample sizes (n~100)and there is minimal difference in estimation of treatment effect when adjusting the model using the factor(s) as continuous covariate(s) vs. stratifying the model with factors at multiple levels.

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 2012 program

2012 JSM Online Program Home

For information, contact jsm@amstat.org or phone (888) 231-3473.

If you have questions about the Continuing Education program, please contact the Education Department.