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. |
Additional standard arguments to model-fitting functions can be passed
to lme
.
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)