vcovFixed: Calculate Variance-Covariance Matrix and Standard Errors of Fixed Effects for an 'VCA' Object
Description
The variance-covariance matrix of fixed effects for the linear mixed model in 'obj' is calculated.
Usage
vcovFixed(obj, quiet = FALSE)
Value
(matrix) corresponding to the variance-covariance matrix of fixed effects
Arguments
obj
(VCA) object for which the variance-covariance matrix of
fixed effects shall be calculated
quiet
(logical) TRUE = will suppress any warning, which will be issued otherwise
Details
The variance-covariance matrix of fixed effects for a linear mixed model corresponds to matrix
\((X^{T}V^{-1}X)^{-}\), where >\(^{T}\)< denotes the transpose operator, >\(^{-1}\)<
the regular matrix inverse, and >\(^{-}\)< the generalized (Moore-Penrose) inverse of a matrix.