Optimal designs for trials with discrete-time survival endpoints

Abstract

Randomized controlled trials require a lot of labor, time, and money. To not waste these efforts and to get scientifically useful results, they need to be carefully planned beforehand.There has been a lack of knowledge on planning designs of longitudinal experiments where events are observed in discrete time, but recently some relevant articles about that topic have been published. In experiments of that type subjects are observed in time periods and a design is a combination of the total number of subjects, the number of time periods they are observed for, and the allocation of subjects to the control and experimental groups. A good design is the combination of these factors that guarantees a sufficient level of statistical power at minimal costs. The optimal design methodology is introduced on a basic level and an example shows that designs based on standard calculations are not necessarily the best choice.