Sample size estimation for the van Elteren test--a stratified Wilcoxon-Mann-Whitney test

Area of Science:

• Biostatistics
• Statistical Methods
• Clinical Trial Design

Background:

• The van Elteren test is a stratified Wilcoxon-Mann-Whitney test used for comparing two treatments within strata.
• Accurate sample size estimation is crucial for the validity and power of clinical studies employing the van Elteren test.

Purpose of the Study:

• To develop and evaluate sample size estimation methods for the asymptotic van Elteren test.
• To provide guidance on selecting appropriate sample size methods based on study design parameters.

Main Methods:

• Development of three large-sample sample size estimation methods for the van Elteren test.
• Application of methods to a real data example for practical illustration.
• Simulation studies to compare the performance of the developed methods.

Main Results:

• The study successfully developed three distinct sample size estimation methods.
• Performance comparison through simulations indicated varying strengths for each method under different conditions.
• A real data example demonstrated the practical application of these methods in study design.

Conclusions:

• The proposed methods offer robust approaches for sample size estimation in studies using the van Elteren test.
• Recommendations are provided for choosing the most suitable method based on study characteristics.
• The study also addresses sample size estimation when stratum fractions are unknown, expanding its applicability.