factorial2x2 (version 0.1.0)

strLgrkPower: Stratified (overall) logrank power

Description

Computes the power for the overall treatment A effect based on the stratified logrank test based on Slud (1994).

Usage

strLgrkPower(n, hrA, hrB, hrAB, avgprob, dig = 2, alpha = 0.05)

Arguments

n

total subjects with n/4 subjects in the C, A, B, and AB groups

hrA

group A to group C hazard ratio

hrB

group B to group C hazard ratio

hrAB

group AB to group C hazard ratio

avgprob

average event probability across the four groups as calculated by the function eventProb

dig

number of decimal places to which we roundDown the critical value corresponding to alpha

alpha

two-sided significance level

Value

mean

logrank mean value

power

logrank power

nevent

expected number of events

Details

The roundDown function is used in conjunction with the dig argument to insure that any rounding of the (negative) critical values will be done conservatively to control the familywise type I error at the desired level.

References

Leifer, E.S., Troendle, J.F., Kolecki, A., Follmann, D. Joint testing of overall and simple effect for the two-by-two factorial design. (2019). Submitted.

Slud, E.V. Analysis of factorial survival experiments. Biometrics. 1994; 50: 25-38.

See Also

roundDown, eventProb

Examples

# NOT RUN {
rateC <- 0.0445
hrA <- 0.80
hrB <- 0.80
hrAB <- 0.72
mincens <- 4.0
maxcens <- 8.4
avgprob <- eventProb(rateC, hrA, hrB, hrAB, mincens, maxcens)$avgprob
n <- 4600
strLgrkPower(n, hrA, hrB, hrAB, avgprob, dig = 2, alpha = 0.05)
# $mean
# [1] -2.537779

# $power
# [1] 0.7182932

# $nevent
# [1] 954.8738
# }