pow {agpower} | R Documentation |
Power for LWYY (fixed sample size)
Description
Function to compute power at one-sided Type I control level alp/2.
Usage
pow(N, bta1, thta, tau, lam0, alp = 0.05, ar = 0.5)
Arguments
N |
Sample size. |
bta1 |
log-transform of rate ratio. |
thta |
Variance of frailty parameter. |
tau |
Expected follow-up time. |
lam0 |
Baseline rate for control. |
alp |
Two-sided alpha-level. |
ar |
Allocation ratio (Number control / Total) |
Details
Note: Approximation breaks down in no event scenario. For example, pow(N=1000, bta1 = log(1), thta = 1, lam0 = 0, tau = 1, alp = 0.05) returns a power of 0.025
Value
The power given the input assumptions.
Examples
pow(N = 500, bta1 = log(0.8), thta = 2, tau = 1, lam0 = 1.1, alp = 0.05)
pow(N = 500, bta1 = log(0.8), thta = 3, tau = 1, lam0 = 1.1, alp = 0.05)
if (require("dplyr") & require("tidyr")) {
assumptions = tibble(alp = 0.05) %>%
crossing(
tau = c(0.8,0.9, 1.0),
RR = c(0.6, 0.7, 0.8),
lam0 = c(3, 3.5),
thta = c(2, 3, 4),
N = c(500, 1000)
) %>%
mutate(pow = pow(N = N, bta1 = log(RR), thta = thta, tau = tau, lam0 = lam0, alp = alp))
assumptions %>% data.frame()
}
[Package agpower version 0.1.2 Index]