erNeeded {agpower} | R Documentation |
Baseline event rate needed (fixed sample size)
Description
Function to compute baseline (control) event rate needed to achieve given power at one-sided Type I control level alp/2.
Usage
erNeeded(
N,
bta1,
thta,
tau,
alp = 0.05,
pow = 0.8,
ar = 0.5,
lam0warning = FALSE
)
Arguments
N |
Sample size. |
bta1 |
log-transform of rate ratio. |
thta |
Variance of frailty parameter. |
tau |
Expected follow-up time. |
alp |
Two-sided alpha-level. |
pow |
Target power. |
ar |
Allocation ratio (Number control / Total). |
lam0warning |
If TRUE indicates how many estimates of lam0 were negative before setting to Inf. Default FALSE. |
Details
Assumes rate ratio < 1 is favourable to treatment. A negative estimated event rate indicates no event rate is sufficient under the input assumptions.
Value
The baseline event rate needed to achieve target power at one-sided Type I control level alpha/2, given the input assumptions.
Examples
erNeeded(N = 500, bta1 = log(0.6), thta = 2, tau = 1, alp = 0.05, pow = 0.8)
erNeeded(N = 500, bta1 = log(0.6), thta = 3, tau = 1, 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),
thta = c(2, 3, 4),
pow = 0.8,
N = c(500, 1000)
) %>%
mutate(er = erNeeded(N = N, bta1 = log(RR), thta = thta, tau = tau, alp, pow))
assumptions %>% data.frame()
}
[Package agpower version 0.1.2 Index]