expand() returns the actual numeric pieces that make up the fitted model:
the response vector, design matrix per submodel, coefficient vectors,
random-effect indicator matrix and BLUPs (when present), residuals, and the
fitted conditional mean and SD vectors. This is the data side of the
symbolized_model surface — the symbolic and matrix
views show what shape the model has; expand() shows what numbers
actually flow through it.
Returned object is classed c("symbolized_expanded", "list") so it has a
compact print() method.
Value
A list with elements (NULL when not applicable to this fit):
yresponse vector of length nXmu-submodel design matrix (n x p_mu)betamu coefficient vector (p_mu)X_sigmasigma-submodel design matrix (n x p_sigma)gammasigma coefficient vector (p_sigma)Z_grandom-effect indicator matrix (n x G), if RE presenturandom-effect BLUPs (G), if RE presenteresiduals (n)mu_hatfitted conditional mean (n)sigma_hatfitted per-observation SD (n)