title: The type II error probability of a group sequential test of efficacy and futility, and considerations for power and sample size.
abstract: For a clinical trial incorporating a group sequential test that allows early stopping for efficacy or futility (GSTEF), the primary hypothesis concerns efficacy. However, the type II error probability of the tests of efficacy is neither specified nor known. The type II error probability of a GSTEF is partitioned into the sum of its component type II error probabilities of futility and efficacy. This partitioning provides transparency, allowing researchers flexibility to set these component error probabilities directly and to know the impact on the total type II error probability and vice versa. This transparency and flexibility should improve the application of GSTEF to clinical trials.
authors: Biostatistics and Research Decision Sciences, Merck Research Laboratories, North Wales, PA 19454-2505, USA. thomas.dobbins@merck.com
authors: Thomas W
authors: TW
authors: Dobbins
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D018447:Medical Futility; D011336:Probability; D018401:Sample Size