Power and Sample Size Calculations

Abstract

Chapter 11 covers sample size and power calculations for testing genetic association, gene-environment interaction, and gene-gene interaction. Asymptotic power for testing a single marker association using the trend test is derived. The power calculations are discussed under perfect linkage disequilibrium or under imperfect linkage disequilibrium. The asymptotic power for Pearson’s test is also given. Asymptotic power is presented using either genotype relative risks or odds ratios. How to use an existing Power Program to calculate sample size and power for single marker association is illustrated. A general approach is described for testing interactions. Then testing gene-environment and gene-gene interactions are treated as special cases. The same Power Program is used to calculate the asymptotic power/sample size for testing gene-gene and gene-environment interactions. Examples are used to illustrate the use of the Power Program.