factorial2x2 (version 0.1.0)

lgrkPower: Unstratified (ordinary) logrank power

Description

Computes the power for the unstratified (ordinary) logrank statistic for two group comparison.

Usage

lgrkPower(hr, nevent, alpha = 0.05, rprob = 0.5)

Arguments

hr

hazard ratio

nevent

expected number of events

alpha

two-sided significance level

rprob

randomization probability

Value

power

logrank power

Details

Uses the formula at the bottom of p.317 from Schoenfeld (Biometrika, 1981) where the beta should be 1 - beta.

References

Schoenfeld, D. The asymptotic properties of nonparametric tests for comparing survival distributions. Biometrika. 1981; 68: 316-319.

Examples

# NOT RUN {
 hr <- 0.5
 nevent <- 98
 lgrkPower(hr, nevent, alpha = 0.05,  rprob = 0.5)
 # $power
 # [1] 0.9293463

# }