lme {lme4} | R Documentation |
This generic function fits a linear mixed-effects model in the formulation described in Laird and Ware (1982) but allowing for nested random effects. The within-group errors are allowed to be correlated and/or have unequal variances.
lme(formula, data, random, ...)
formula |
a two-sided linear formula object describing the
fixed-effects part of the model, with the response on the left of a
~ operator and the terms, separated by + operators, on
the right. |
data |
an optional data frame containing the variables named in
formula , random , correlation , weights , and
subset . By default the variables are taken from the
environment from which lme is called. |
random |
optionally, 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 factor; or (iii) a named list of formulas. |
... |
Optional arguments for methods. Currently none are used. |
A new version of the function called lme1
is in the development
versions of this package. The lme1
function has the same
argument sequence as lme
but produces an object with an
lmeRep
representation of the model. The object
produced by lme
uses the ssclme
representation.
Additional standard arguments to model-fitting functions can be passed
to lme
or lme1
.
corStruct
object describing
the within-group correlation structure. See the documentation of
corClasses
for a description of the available corStruct
classes. Defaults to NULL
, corresponding to no within-group
correlations.varFunc
object or one-sided formula
describing the within-group heteroscedasticity structure. If given as
a formula, it is used as the argument to varFixed
,
corresponding to fixed variance weights. See the documentation on
varClasses
for a description of the available varFunc
classes. Defaults to NULL
, corresponding to homocesdatic
within-group errors.data
that should be used in the fit. This can be a logical
vector, or a numeric vector indicating which observation numbers are
to be included, or a character vector of the row names to be
included. All observations are included by default."REML"
the model is fit by
maximizing the restricted log-likelihood. If "ML"
the
log-likelihood is maximized. Defaults to "REML"
.NA
s. The default action (na.fail
) causes
lme
to print an error message and terminate if there are any
incomplete observations.lmeControl
.
Defaults to an empty list.TRUE
the corresponding
components of the fit (the model frame, the model matrices)
are returned.
An lme-class{lme}
object.
data(bdf) fm <- lme(langPOST ~ IQ.ver.cen + avg.IQ.ver.cen, data = bdf, random = ~ IQ.ver.cen | schoolNR) summary(fm)