Validated frameworks; observed GMR not relevant [Two-Stage / GS Designs]

posted by Silva – Portugal, 2017-03-09 01:26  – Posting: # 17143
Views: 9,493

Hi Helmut

Trying to learn technical issues of TSD.

In the example you gave:

library(Power2Stage)
 power.2stage(CV=0.2, n1=12, alpha=c(0.0294, 0.0294), theta0=1.25,
              targetpower=0.8, pmethod="shifted", nsims=1e6)$pBE
 # [1] 0.046352
# n1 within validated range: TIE <0.05.

why the use of theta0 as 1.25 and not as GMR value? I understand the use of GMR of 0.95 for Potvin B method (as it was validated with this assumption), but don´t understant the meaning of theta0.

According to Power2Stage manual, theta 0 corresponds to the True ratio of T/R for simulating. (Defaults to the GMR argument if missing).

What is the meaning of "True ratio of T/R for simulating" and what is the difference for GMR?

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