This function performs the sample size calculation for a mixed model of
repeated measures with AR(1) correlation structure. See Lu, Luo, & Chen
(2008) for parameter definitions and other details.
Usage
power.mmrm.ar1(N = NULL, rho = NULL, ra = NULL, sigmaa = NULL,
rb = NULL, sigmab = NULL, lambda = 1, times = 1:length(ra),
delta = NULL, sig.level = 0.05, power = NULL,
alternative = c("two.sided", "one.sided"), tol = .Machine$double.eps^2)
Arguments
N
total sample size
rho
AR(1) correlation parameter
ra
retention in group a
sigmaa
standard deviation of observation of interest in group a
rb
retention in group a (assumed same as ra if left blank)
sigmab
standard deviation of observation of interest in group b. If
NULL, sigmab is assumed same as sigmaa. If not NULL,
sigmaa and sigmab are averaged.
lambda
allocation ratio
times
observation times
delta
effect size
sig.level
type one error
power
power
alternative
one- or two-sided test
tol
numerical tolerance used in root finding.
Details
See Lu, Luo, & Chen (2008).
Value
The number of subject required per arm to attain the specified
power given sig.level and the other parameter estimates.
Author(s)
Michael C. Donohue
References
Lu, K., Luo, X., Chen, P.-Y. (2008) Sample size estimation for
repeated measures analysis in randomized clinical trials with missing data.
International Journal of Biostatistics, 4, (1)