Fig. 1

Contour plot for the percent change in sample size required to achieve 80% power to detect a fixed treatment effect across a range of parameters that change measurement error variability differentially with respect to follow-up and treatment condition at follow-up. The x-axis displays values for the parameter for changing variability at follow-up (λ₂), the y-axis displays values for the parameter for changing variability for the treatment condition at follow-up (λ₃). The point plotted at (1,1) corresponds to 0% change in sample size due to no change in variability at follow-up or treatment condition at follow-up