This function is a constructor for the
reStruct class,
representing a random effects structure and consisting of a list of
pdMat
objects, plus a
settings attribute containing
information for the optimization algorithm used to fit the associated
mixed-effects model.
USAGE:
reStruct(object, pdClass, REML, data)
REQUIRED ARGUMENTS:
object
any of the following: (i) a one-sided formula of the form
~x1+...+xn | g1/.../gm, with
x1+...+xn specifying the
model for the random effects and
g1/.../gm the grouping
structure (
m may be equal to 1, in which case no
/ is
required). The random effects formula will be repeated for all levels
of grouping, in the case of multiple levels of grouping; (ii) a list of
one-sided formulas of the form `~x1+...+xn | g', with possibly
different random effects models for each grouping level. The order of
nesting will be assumed the same as the order of the elements in the
list; (iii) a one-sided formula of the form `~x1+...+xn', or a
pdMat object with a formula (i.e. a non-
NULL value for
formula(object)), or a list of such formulas or
pdMat
objects. In this case, the grouping structure formula will be derived
from the data used to fit the mixed-effects model, which should
inherit from class
groupedData; (iv) a named list of formulas or
pdMat objects as in (iii), with the grouping factors as
names. The order of nesting will be assumed the same as the order of
the order of the elements in the list; (v) an
reStruct object.
OPTIONAL ARGUMENTS:
pdClass
an optional character string with the name of the
pdMat class to be used for the formulas in
object. Defaults to
"pdSymm" which corresponds to a
general positive-definite matrix.
REML
an optional logical value. If
TRUE, the associated
mixed-effects model will be fitted using restricted maximum
likelihood; else, if
FALSE, maximum likelihood will be
used. Defaults to
FALSE.
data
an optional data frame in which to evaluate the variables
used in the random effects formulas in
object. It is used to
obtain the levels for
factors, which affect the dimensions and
the row/column names of the underlying
pdMat objects. If
NULL, no attempt is made to obtain information on
factors appearing in the formulas. Defaults to the parent
frame from which the function was called.
VALUE:
an object inheriting from class
reStruct, representing a random
effects structure.
SEE ALSO:
,
,
EXAMPLES:
rs1 <- reStruct(list(Dog = ~day, Side = ~1), data = Pixel)
rs1
fm1 <- lme(distance ~ age, data=Orthodont) # random is ~ age
fm1$modelStruct$reStruct