gbounds {triggerstrategy}

Critical boundary in group sequential trials

Description

This function computes the critical boundaries and the error spent until each stage in group sequential trials

Usage

gbounds(t, iuse = 1, alpha = 0.05, phi = rep(1, length(alpha)))

Arguments

t

a vector of information times

iuse

a number of the type of the error spending function, from -2, -1, 1, 2, 3, 4

alpha

a number of type I error rate

phi

a parameter for the power family or the HSD gamma family

Details

If the original Pocock is implemented, we specify iuse=-2. If the original OBrien-Flemming is implemented, we specify iuse=-1.

Value

a list of two vectors: bd critical boundaries, er error spent until each stage

Author(s)

Jiangtao Gou

Examples

t<-c(0.5,0.8,1)
iuse <- 4
gbounds(t=t, iuse=iuse)
gbounds(t=(1:5)/5, iuse=4, alpha=0.01, phi=-4)
gbounds(t=(1:5)/5, iuse=-2, alpha=0.01)