| powerfamily {OptGS} | R Documentation |
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) |
J |
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) |
Details
powerfamily uses the extended power-family of group-sequential tests. A description of the extended power-family is provided in Wason (2012).
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 |
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
##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)