mHP.b {ASSISTant}

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

Description

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

Usage

mHP.b(prevalence, N, cov.J, mu.prime, Sigma.prime, alpha, btilde, theta)

Arguments

prevalence

the vector of prevalences between 0 and 1 summing to 1. J, the number of groups, is implicitly the length of this vector and should be at least 2.

N

a three-vector of total sample size at each stage

cov.J

the 3 x 3 covariance matrix for Z_J at each of the three stages

mu.prime

a list of J mean vectors, each of length J-1 representing the conditional means of all the other Z_j given Z_i. This mean does not account for the conditioned value of Z_i and so has to be multiplied by that during use!

Sigma.prime

a list of J covariance matrices, each J-1 by J-1 representing the conditional covariances all the other Z_j given Z_i

alpha

the amount of type I error to spend

btilde

the futility boundary

theta

the effect size on the probability scale