cpboundary: The stopping boundary based on the conditional power criteria

In PWEALL: Design and Monitoring of Survival Trials Accounting for Complex Situations

The stopping boundary based on the conditional power criteria

Description

This will calculate the stopping boundary based on the conditional power criteria, i.e. if observed HR is above the boundary, the conditional power will be lower than the designated level. All the calculation is based on the proportional hazards assumption and the Cox model.

Usage

cpboundary(Dplan=300,alpha=0.05,two.sided=1,pi1=0.5,cpcut=c(0.2,0.3,0.4),
            BetaD=log(0.8),Beta0=log(1),prop=seq(0.1,0.9,by=0.1))

Arguments

Dplan	Planned number of events at study end
alpha	Type 1 error rate
two.sided	=1 two-sided test and =0 one-sided test
pi1	Allocation probability for the treatment group
cpcut	the designated conditional power level
BetaD	designed log hazard ratio, i.e. under alternative hypothesis
Beta0	null log hazard ratio, i.e. under null hypothesis
prop	proportion of Dplan observed

Details

This will calculate the stopping boundary based on the conditional power criteria, i.e. if observed HR is above the boundary, the conditional power will be lower than the designated level. All the calculation is based on the proportional hazards assumption and the Cox model.

Value

CPTbound	Boundary based on the conditional power under current trend
CPNbound	Boundary based on the conditional power under null hypothesis
CPDbound	Boundary based on the conditional power according to design, i.e. under alternative hypothesis

Note

This will calculate the stopping boundary based on the conditional power criteria

Author(s)

Xiaodong Luo

References

Halperin, Lan, Ware, Johnson and DeMets (1982). Controlled Clinical Trials.

See Also

cp,cpstop

Examples

###Calculate the stopping boundary at 10-90 percent of the target 300 events 
###when the condition power are c(0.2,0.3,0.4) with 
###2:1 allocation ratio between the treatment group and the control group
cpboundary(pi1=2/3)

PWEALL documentation built on Aug. 9, 2023, 9:08 a.m.