nNeeded {agpower} | R Documentation |
Function to compute sample size needed to achieve target power
Description
Computes sample size needed to achieve target power at one-sided Type I control level alp/2.
Usage
nNeeded(bta1, thta, tau, lam0, alp = 0.05, pow = 0.8, ar = 0.5)
Arguments
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. |
pow |
Target power. |
ar |
Allocation ratio (Number control / Total) |
Value
The sample size required given the input assumptions to achieve target power.
Examples
nNeeded(bta1 = log(0.8), thta = 1, tau = 0.8, lam0 = 3.5, alp = 0.05, pow = 0.8)
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),
pow = 0.8
) %>%
mutate(N = nNeeded(bta1 = log(RR), thta = thta, tau = tau, lam0 = lam0, alp = alp, pow = pow))
assumptions %>% data.frame()
}
[Package agpower version 0.1.2 Index]