object
an object inheriting from class nlmeStruct,
representing a list of mixed-effects model components, such as
reStruct, corStruct, and varFunc objects.
level
an optional integer vector giving the level(s) of grouping
to be used in extracting the residuals from object. Level
values increase from outermost to innermost grouping, with
level zero corresponding to the population fitted values.
conLin
an optional condensed linear model object, consisting of
a list with components "Xy", corresponding to a regression
matrix (X) combined with a response vector (y), and
"logLik", corresponding t