
76 Sample Size Calculations for Clustered and Longitudinal Outcomes
3.3.7 Sample Size Estimation under Financial Constraints
In clinical trials, sample size is generally estimated based on the number of
subjects necessary to detect clinically meaningful differences between treat-
ment groups. However, budget constraint is a challenge faced by investigators
in planning almost every clinical trial. Sample size needs to be estimated by
incorporating costs for recruiting and measuring subjects in repeated mea-
surement studies [23, 24, 25, 26, 27].
Lai et al. [23] investigated how to determine the optimal number of subjects
and number of measurements per ...