Compute the power of a simple cluster randomized trial with a count outcome, or determine parameters to obtain a target power.
crtpwr.2rate(alpha = 0.05, power = 0.8, m = NA, py = NA, r1 = NA,
r2 = NA, cvb = NA, tol = .Machine$double.eps^0.25)The level of significance of the test, the probability of a Type I error.
The power of the test, 1 minus the probability of a Type II error.
The number of clusters per condition. It must be greater than 1.
The number of person-years of observation per cluster.
The expected mean event rate per unit time in the treatment group.
The mean event rate per unit time in the control group.
The between-cluster coefficient of variation.
Numerical tolerance used in root finding. The default provides at least four significant digits.
The computed argument. #' #' @examples # Find the number of clusters per condition needed for a trial with alpha = .05, # power = 0.8, 10 person-years per cluster, rate in condition 1 of .1 and condition 2 of .2, and cvb = 0.1. crtpwr.2rate(py=10, r1=.1, r2=.2, cvb=.1) # # The result, showimg m of greater than 24, suggests 25 clusters per condition should be used.
Jonathan Moyer (jon.moyer@gmail.com)