RandEff_to_alpha012: Transform random effects to alpha

In PMildenb/SteppedPower: Power Calculation for Stepped Wedge Designs

Transform random effects to alpha

Description

#' Transforms standard deviations of random effects into a correlation structure specified by \alpha_0, \alpha_1, \alpha_2 as defined in Li et al. (2018).

Usage

RandEff_to_alpha012(sigResid, tau, gamma, psi)

Arguments

sigResid	Residual standard deviation on individual level
tau	standard deviation of random cluster intercept
gamma	standard deviation of random time effect
psi	standard deviation of random subject specific intercept

Value

a list containing four named elements (possibly vectors or matrices): alpha0, alpha1, alpha2 specify a correlation structure. SigMarg denotes the marginal standard deviation

References

Li, F., Turner, E. L., & Preisser, J. S. (2018).
Sample size determination for GEE analyses of stepped wedge cluster randomized trials.
Biometrics, 74(4), 1450-1458. DOI: 10.1111/biom.12918

See Also

RandEff_to_icc(), icc_to_RandEff() or alpha012_to_RandEff()

Examples

RandEff_to_alpha012(sigResid=sqrt(11), tau=4, gamma=3, psi=2)

## The function is vectorised:
RandEff_to_alpha012(sigResid = matrix(c(0,1,2,3,4,5), 2, 3),
                    tau      = matrix(c(1,1,1,0,0,0), 2, 3),
                    gamma    = matrix(c(0,0,1,0,0,1), 2, 3),
                    psi      = matrix(c(0,1,1,0,0,1), 2, 3))

PMildenb/SteppedPower documentation built on Nov. 24, 2024, 3:06 a.m.