TY - JOUR AU - Bratton, Daniel J. AU - Parmar, Mahesh K. B. AU - Phillips, Patrick P. J. AU - Choodari-Oskooei, Babak PY - 2016 DA - 2016/07/02 TI - Type I error rates of multi-arm multi-stage clinical trials: strong control and impact of intermediate outcomes JO - Trials SP - 309 VL - 17 IS - 1 AB - The multi-arm multi-stage (MAMS) design described by Royston et al. [Stat Med. 2003;22(14):2239–56 and Trials. 2011;12:81] can accelerate treatment evaluation by comparing multiple treatments with a control in a single trial and stopping recruitment to arms not showing sufficient promise during the course of the study. To increase efficiency further, interim assessments can be based on an intermediate outcome (I) that is observed earlier than the definitive outcome (D) of the study. Two measures of type I error rate are often of interest in a MAMS trial. Pairwise type I error rate (PWER) is the probability of recommending an ineffective treatment at the end of the study regardless of other experimental arms in the trial. Familywise type I error rate (FWER) is the probability of recommending at least one ineffective treatment and is often of greater interest in a study with more than one experimental arm. SN - 1745-6215 UR - https://doi.org/10.1186/s13063-016-1382-5 DO - 10.1186/s13063-016-1382-5 ID - Bratton2016 ER -