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Activity Number:
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51
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Type:
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Contributed
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Date/Time:
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Sunday, August 11, 2002 : 4:00 PM to 5:50 PM
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Sponsor:
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Biometrics Section*
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| Abstract - #301281 |
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Title:
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Sample Size Estimation for GEE Method for Comparing Slopes in Repeated Measurements Data
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Author(s):
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Sin-Ho Jung*+ and Chul Ahn
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Affiliation(s):
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Duke University and University of Texas Medical School
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Address:
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, , , ,
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Keywords:
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AR(1) ; Compound symmetry ; Iid working correlation ; Independent missing ; Monotone missing ; Variable measurement times
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Abstract:
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Sample size calculation is an important component at the design stage of clinical trials. Controlled clinical trials often use a repeated measurement design in which individuals are randomly assigned to treatment groups and followed-up for measurements at intervals across a treatment period of fixed duration. In studies with repeated measurements, one of the popular primary interests is the comparison of the rates of change in a response variable between groups. Statistical models for calculating sample sizes for repeated measurement designs often fail to take into account the impact of missing data correctly. In this paper, we propose to use the GEE method in comparing the rates of changes in repeated measurements and introduce closed-form formulas for sample size and power that can be calculated using a scientific calculator. Since the sample size formula is based on asymptotic theory, we investigate the performance of the estimated sample size in practical settings through simulations.
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- Authors who are presenting talks have a * after their name.
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