if groups is missing, it returns the Dim attribute of
object; otherwise, calculates the dimensions associated with
the grouping factor.
Usage
Dim(object, groups)
Arguments
object
an object inheriting from class corStruct,
representing a correlation structure.
groups
an optional factor defining the grouping of the
observations; observations within a group are correlated and
observations in different groups are uncorrelated.
Value
a list with components:
Nlength of groups
Mnumber of groups
maxLenmaximum number of observations in a group
sumLenSqsum of the squares of the number of observations per
group
lenan integer vector with the number of observations per
group
startan integer vector with the starting position for the
observations in each group, beginning from zero