strLgrkPower: Stratified (overall) logrank power
In factorial2x2: Design and Analysis of a 2x2 Factorial Trial

Description Usage Arguments Details Value Author(s) References See Also Examples

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

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

`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

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.

`mean`	logrank mean value
`power`	logrank power
`nevent`	expected number of events

Eric Leifer, James Troendle

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.

roundDown, eventProb

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