construct_CovBlk: Construct a Single Block of the Covariance Matrix

In PMildenb/SteppedPower: Power Calculation for Stepped Wedge Designs

Construct a Single Block of the Covariance Matrix

Description

Constructs the covariance matrix for multiple measurements of the same cluster. This function is usually called by 'construct_CovMat' and is not designed to be used directly.

Usage

construct_CovBlk(sigma, tau = NULL, eta = NULL, AR = NULL, rho = NULL)

Arguments

sigma	numeric (vector of length 'timepoints'), residual error
tau	numeric (vector of length 'timepoints'), standard deviation of random intercepts
eta	numeric (vector of length 'timepoints'), standard deviation of random slope
AR	numeric, vector containing up to three values, each between 0 and 1. Defaults to NULL. It defines the AR(1)-correlation of random effects. The first element corresponds to the cluster intercept, the second to the treatment effect and the third to subject specific intercept. If only one element is provided, autocorrelation of all random effects is assumed to be the same. *Currently not compatible with 'rho'!=0 !*
rho	numeric (scalar), correlation of 'tau' and 'eta'. The default is no correlation.

Value

a block of a covariance matrix, corresponding to intra-cluster covariance over time for one cluster

Examples

construct_CovBlk(sigma=rep(2,5), tau=rep(1,5))

construct_CovBlk(sigma=rep(2,5),
                tau=rep(.5,5), eta=c(0,0,1,1,1),
                AR=c(.5, 1))

PMildenb/SteppedPower documentation built on Sept. 20, 2023, 4:57 a.m.