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This will calculate the conditional power given the observed log hazard ratio based on Cox model
cp(Dplan=300,alpha=0.05,two.sided=1,pi1=0.5,Obsbeta=log(seq(1,0.6,by=-0.01)),
BetaD=log(0.8),Beta0=log(1),prop=seq(0.1,0.9,by=0.1))
Conditional power under current trend
Conditional power under null hypothesis
Conditional power according to design, i.e. under alternative hypothesis
Planned number of events at study end
Type 1 error rate
=1 two-sided test and =0 one-sided test
Allocation probability for the treatment group
observed log hazard ratio
designed log hazard ratio, i.e. under alternative hypothesis
null log hazard ratio, i.e. under null hypothesis
proportion of Dplan observed
Xiaodong Luo
This is to calculated conditional power at time point when certain percent of target number of event has been observed and an observed log hazard ratio is provided.
Halperin, Lan, Ware, Johnson and DeMets (1982). Controlled Clinical Trials.
cpboundary,cpstop
###Calculate the CP at 10-90 percent of the target 300 events when the observed HR
###are seq(1,0.6,by=-0.01) with 2:1 allocation
###ratio between the treatment group and the control group
cp(pi1=2/3)
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