unconditional versus conditional
TwoSampleSurvival.Conditional(alpha,beta,lam1,lam2,eta1,eta2,k,ttotal,taccrual,g1,g2)significance level
power = 1-beta
the hazard rates of control group
the hazard rates of a test drug
in control group, the losses are exponentially distributed with loss hazard rate eta1
in treatment group, the losses are exponentially distributed with loss hazard rate eta2
k=n1/n2 sample size ratio
Total trial time
accrual time period
parameter for the entry distribution of control group, which is uniform patient entry with gamma1=0.
parameter for the entry distribution of treatment group, which is uniform patient entry with gamma2=0.
Chow SC, Shao J, Wang H. Sample Size Calculation in Clinical Research. New York: Marcel Dekker, 2003