Impact of incorrect designation of working correlation structure matrix on sample size estimation in 2×2 cross design: a simulation study.
10.12122/j.issn.1673-4254.2025.11.22
- Author:
Peiyu ZHANG
1
;
Ziheng XIE
1
;
Yan ZHUANG
1
Author Information
1. Department of Biostatistics, School of Public Health, Southern Medical University, Guangzhou 510515, China.
- Publication Type:Journal Article
- Keywords:
2×2 crossover trials;
generalized estimation equation design;
sample size estimation;
working correlation structure matrix
- MeSH:
Sample Size;
Monte Carlo Method;
Humans;
Cross-Over Studies;
Computer Simulation;
Research Design;
Bias
- From:
Journal of Southern Medical University
2025;45(11):2495-2503
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVES:To investigate the impact of incorrect specification of the working correlation structure matrix on estimated sample size in a 2×2 crossover design based on the generalized estimating equation (GEE).
METHODS:Based on Monte Carlo simulation, the influence of incorrect specification of the work-related structure matrix on the sample size estimation under different conditions was evaluated after controlling the total sample size n, the proportion of subjects assigned to AB sequence (s=1) θ, the correlation coefficient ρ, and the placebo effect OR. Bias and mean square error (MSE) were used to assess the difference between the sample size estimates and the theoretical values.
RESULTS:When the correctly specified working correlation structure matrix is independent, the sample size estimation effect of correctly specifying the working correlation structure matrix is better than that of incorrect specification. But when the correctly specified working correlation structure matrix is equal and the correlation coefficient is closer to 0, with other factors being smaller (n≤50, θ≤0.5, OR=2 in this article), there is a situation where the bias of the sample size estimation value for the correctly specified working correlation structure matrix is greater than the bias for the incorrectly specified working correlation structure matrix.
CONCLUSIONS:Under most conditions, incorrectly specifying the working correlation structure matrix can cause the estimated sample size to deviate significantly from the theoretical value, but under certain conditions, the impact of incorrectly specifying the working correlation structure matrix can be small on the estimated sample size.
