powerfamily: Finding extended power-family group-sequential designs

Description

powerfamily is used to find a one-sided extended power-family group-sequential design

Usage

powerfamily(futility = 0, efficacy = 0, delta0 = 0, delta1 = 1/3, J = 2, sigma = 1, sd.known = TRUE, alpha = 0.05, power = 0.9)

Arguments

futility

shape parameter for futility boundaries (default: 0)

efficacy

shape parameter for efficacy boundaries (default: 0)

delta0

mean difference in treatment effect under the null hypothesis (default: 0)

delta1

clinically relevant difference used to power the trial (default: 1/3)

number of stages in the trial (default: 2)

sigma

assumed standard deviation of treatment responses (default: 1)

sd.known

logical value indicating if sigma will be treated as known; if FALSE, a quantile substitution method will be used to modify the stopping boundaries (default TRUE)

alpha

one-sided type-I error rate required (default: 0.05)

power

power required (default: 0.9)

Value

groupsize: the number of patients required per arm, per stage
futility: the futility boundaries for the design
efficacy: the efficacy boundaries for the design
ess: the expected sample size at the delta0; the expected sample size at the delta1; and the maximum expected sample size
typeIerror: the actual type-I error rate of the design
power: the actual power of the design

Details

powerfamily uses the extended power-family of group-sequential tests. A description of the extended power-family is provided in Wason (2012).

References

Wason, J.M.S. OptGS: an R package for finding near-optimal group-sequential designs. Journal of Statistical Software, 66(2), 1-13. http://www.jstatsoft.org/v66/i02/

Examples

Run this code

##Find a three-stage design that has shape parameters -0.5 and 0.5.
threestagedesign=powerfamily(J=3,futility=-0.5,efficacy=0.5) 
plot(threestagedesign)

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