mHP.btilde {ASSISTant}R Documentation

Compute the futility boundary (modified Haybittle-Peto) for the first two stages


The futility boundary btilde is computed by solving (under the alternative)


mHP.btilde(beta, cov.J)



the type II error


the 3 x 3 covariance matrix


P(\tilde{Z}_J^1≤\tilde{b} or \tilde{Z}_J^2≤\tilde{b}) = εβ

where the superscripts denote the stage and ε is the fraction of the type I error (α) spent and β is the type II error. We make use of the joint normal density of Z_{J} (the overall group) at each of the three stages and the fact that the \tilde{Z_J} is merely a translation of Z_J. So here the calculation is based on a mean of zero and has to be translated during use!


Adaptive Choice of Patient Subgroup for Comparing Two Treatments by Tze Leung Lai and Philip W. Lavori and Olivia Yueh-Wen Liao. Contemporary Clinical Trials, Vol. 39, No. 2, pp 191-200 (2014).

[Package ASSISTant version 1.4.2 Index]