Does unequal alpha distribution make sense? [Two-Stage / GS Designs]

posted by Dr_Dan  – Germany, 2015-05-29 10:33 (3610 d 04:17 ago) – Posting: # 14879
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Dear Helmut
For a non-statistician the whole problem is very complicated. The method according to Haybittle/Peto

Stage I:  0.001 leading to 99.8% CI
Stage II: 0.049 leading to 90.2% CI

may lead to unacceptable inflation of the TIE, so far I understood. As you explained in your pile of half-baked manuscripts you explored adjusted alphas which maintain the TIE. For a “type 1” TSD, GMR 0.95, target power 80%, α1 0.001 you found an adjusted α2 of 0.0413 suitable to maintain the patient’s risk. Using this method which kind of CI do you have for the second stage?

Stage I:  0.001 leading to 99.8% CI
Stage II: 0.0413 leading to 9?.?% CI ???

For the sample size calculation for the second stage you use the GMR 0.95 or the GMR as calculated from stage I results?

Kind regards
Dr_Dan

Kind regards and have a nice day
Dr_Dan

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