6. Phase III Trial Design

  1. Guosheng Yin

Published Online: 9 JAN 2012

DOI: 10.1002/9781118183335.ch6

Clinical Trial Design: Bayesian and Frequentist Adaptive Methods

Clinical Trial Design: Bayesian and Frequentist Adaptive Methods

How to Cite

Yin, G. (2011) Phase III Trial Design, in Clinical Trial Design: Bayesian and Frequentist Adaptive Methods, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9781118183335.ch6

Publication History

  1. Published Online: 9 JAN 2012
  2. Published Print: 19 DEC 2011

ISBN Information

Print ISBN: 9780470581711

Online ISBN: 9781118183335



  • binary endpoints;
  • continuous data;
  • group sequential methods;
  • phase III clinical trials;
  • randomization


Phase III clinical trials are randomized and controlled studies that directly compare the investigational drug with the current “gold standard” treatment or a placebo when there is no standard of care. In a phase III trial, sample size calculation is the most critical component of the study design. In clinical trials with continuous or binary endpoints, responses of patients are typically observed immediately or shortly after treatment. Phase III trials often collect such time-to-event data to examine whether there are survival differences between treatment groups. Continuous data monitoring refers to a fully sequential analysis of the accumulating data after observing every single outcome, which, however, may be practically infeasible. Group sequential methods offer a compromise between trial flexibility and practicality. The goal of randomization in a clinical trial is to balance patients in each treatment arm, so that patients in different groups are “alike” on average.

Controlled Vocabulary Terms

continuous data; randomization; sequential analysis