This is the program for the 2010 Joint Statistical Meetings in Vancouver, British Columbia.

Abstract Details

Activity Number: 669
Type: Contributed
Date/Time: Thursday, August 5, 2010 : 10:30 AM to 12:20 PM
Sponsor: Biopharmaceutical Section
Abstract - #307606
Title: Power Analyses for Negative Binomial Models with Application to Multiple Sclerosis Clinical Trials
Author(s): Mallikarjuna Rettiganti*+ and Haikady Nagaraja
Companies: The Ohio State University and The Ohio State University
Address: , Columbus, OH, 43210,
Keywords: Negative Binomial Models ; Likelihood Ratio, Score and Wald Tests ; Power analysis ; Sample size ; Relapsing Remitting Multiple Sclerosis ; Clinical Trials
Abstract:

Brain lesion count based on magnetic resonance imaging (MRI) is a key variable in the study of the disease progression of relapsing remitting multiple sclerosis (RRMS). We develop negative binomial (NB) models for such count data arising in RRMS Parallel Group (PG) and Baseline vs. Treatment (BVT) trials, and describe the resulting likelihood ratio test (LRT), Rao's score test (RST) and Wald tests. We use the univariate NB model for PG trials and bivariate NB model for BVT trials. We perform power analyses and sample size estimation using the simulated exact distributions of the test statistics which maintain the desired significance levels unlike the asymptotic tests used before. Generally, the LRT and one of the Wald tests with exact critical values perform well and provide substantial reduction in sample sizes when compared to those proposed earlier using nonparametric tests.


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