computeDGivenXi {sp23design}

Given the estimates of the \pi and \theta, compute d.

Description

This function computes d via

d(\pi,\xi)=\{ \pi_0 a + (1-\pi_0)\} - \{\pi_1 abc + (1-\pi_1)b \}

Usage

computeDGivenXi(piVec, xiVec)

Arguments

piVec

The two-element vector of (\pi_0, \pi_1)

xiVec

The three-element vector of (a=e^\alpha, b=e^\beta, c=e^\gamma)

Details

This is an approximation to the hazard ratio

Value

The computed value of d, a scalar

Author(s)

Mei-Chiung Shih, Balasubramanian Narasimhan, Pei He

References

Lai, Tze Leung and Lavori, Philip W. and Shih, Mei-Chiung. Sequential Design of Phase II-III Cancer Trials, Statistics in Medicine, Volume 31, issue 18, p.1944-1960, 2012.