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Frequency and Distribution of Crossovers in Caenorhabditis elegans Meiosis by SNP Genotyping using Real-time PCR

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Sample size determination for testing equality in Poisson frequency data under an AB/BA crossover trial.

Kung-Jong Lui¹

¹Department of Mathematics and Statistics, College of Sciences, San Diego State University, San Diego, CA 92182-7720, USA. kjl@rohan.sdsu.edu

Pharmaceutical Statistics

|February 1, 2013

Summary

This summary is machine-generated.

This study provides sample size calculations for AB/BA crossover trials using Poisson distribution. An exact test is recommended for large treatment effects, while an asymptotic test is suitable for smaller effects to reduce patient numbers.

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Area of Science:

Biostatistics
Clinical Trial Design
Statistical Methods

Background:

Accurate sample size calculation is crucial for the efficiency and validity of clinical trials.
AB/BA crossover designs are commonly used in clinical research, particularly for chronic conditions.
The Poisson distribution is often applicable for count data, such as event frequencies.

Purpose of the Study:

To develop and evaluate sample size calculation procedures for testing equality in AB/BA crossover designs assuming a Poisson distribution.
To compare the accuracy of exact and asymptotic test procedures for sample size determination.
To provide guidance on selecting the appropriate sample size method based on study parameters.

Main Methods:

Development of sample size calculation procedures based on both exact and asymptotic test procedures.
Utilization of Monte Carlo simulations to demonstrate and assess the accuracy of the proposed formulae.
Evaluation of sample size accuracy concerning statistical power under various scenarios.

Main Results:

The asymptotic test procedure for sample size calculation can lose accuracy when the relative treatment effect and intraclass correlation are large.
For large treatment effects, the exact test procedure is recommended for accurate sample size calculation.
The asymptotic test procedure is valid and can reduce required sample size when the relative treatment effect is small.

Conclusions:

The choice between exact and asymptotic sample size calculations in AB/BA crossover trials depends on the magnitude of the relative treatment effect and intraclass correlation.
The exact test procedure offers greater accuracy for larger effects, while the asymptotic procedure provides efficiency for smaller effects.
Practical application is illustrated with a double-blind randomized crossover trial comparing salmeterol with placebo for asthma exacerbations.