R/TwoSampleSurvival.NIS.R

In TrialSize: R Functions for Chapter 3,4,6,7,9,10,11,12,14,15 of Sample Size Calculation in Clinical Research

TwoSampleSurvival.NIS <-
function(alpha,beta,lam1,lam2,k,ttotal,taccrual,gamma,margin){

variance1<-lam1^2*(1+gamma*exp(-lam1*ttotal)*(1-exp((lam1-gamma)*taccrual))/((lam1-gamma)*(1-exp(-gamma*taccrual))))^-1
variance2<-lam2^2*(1+gamma*exp(-lam2*ttotal)*(1-exp((lam2-gamma)*taccrual))/((lam2-gamma)*(1-exp(-gamma*taccrual))))^-1

print(variance1)
print(variance2)

n2=(qnorm(1-alpha)+qnorm(1-beta))^2*(variance1/k+variance2)/(lam2-lam1-margin)^2
n2
}