Abstract #300510

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JSM 2003 Abstract #300510
Activity Number: 473
Type: Contributed
Date/Time: Thursday, August 7, 2003 : 10:30 AM to 12:20 PM
Sponsor: Biopharmaceutical Section
Abstract - #300510
Title: Schemes for Calculating Ordered Categorical Score Reductions and Sample Size Considerations
Author(s): Lin Fei*+
Companies: Procter & Gamble Company
Address: 8700 Mason-Montgomery Rd., Mason, OH, 45040-9760,
Keywords: ordered categories ; ridit analysis ; proportional odds ; mathematical programming
Abstract:

In designing clinical studies, we often need to conduct power analyses for ordered categorical data when a desired treatment effect is expressed in terms of a mean change, in disease severity scores for example. This article first describes how a change in mean score can be translated into a shift in multinomial probability distributions. Schemes to construct multinomial distributions that meet such mean value constraints are discussed, along with sample size considerations for analyses of ordered categorical data. Specifically, sample size calculations are presented and compared among the following three test procedures: chi-squared test, ridit analysis, and a likelihood-based score test of proportional odds model. Finally, upper and lower bounds for such sample sizes are presented.

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