A Comment on Sample Size Calculation for Analysis of Covariance in Parallel Arm StudiesGuogen Shan1* and Changxing Ma2
- *Corresponding Author:
- Guogen Shan
Epidemiology and Biostatistics Program, Department of Environmental and Occupational Health
School of Community Health Sciences
University of Nevada Las Vegas, Las Vegas, NV 89154, USA
E-mail: [email protected]
Received date: December 17, 2013; Accepted date: January 09, 2014; Published date: January 16, 2014
Citation: Shan G, Ma C (2014) A Comment on Sample Size Calculation for Analysis of Covariance in Parallel Arm Studies. J Biomet Biostat 5: 184. doi: 10.4172/2155-6180.1000184
Copyright: © 2014 Shan G, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are are credited.
We compare two sample size calculation approaches for analysis of covariance with one covariate. Exact simulation studies are conducted to compare the sample size calculation based on an approach by Borm et al. (2007) (referred to as the B approach) and an exact approach (referred to as the F approach). Although the B approach and the F approach have similar performance when the correlation coefficient is small, the F approach generally has a more accurate sample size calculation as compared to the B approach. Therefore, the F approach for sample size calculation is generally recommended for use in practice.