lme4 (version 0.5-2)

lme: Fit linear mixed-effects models

Description

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.

Usage

lme(formula, data, random, correlation, weights, subset,
    method, na.action, control, model, x)

Arguments

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

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 m

correlation

an optional corStruct object describing the within-group correlation structure. See the documentation of corClasses for a description of the available corStruct classes. Defaults to NULL, cor

weights

an optional 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 do

subset

an optional expression indicating the subset of the rows of 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 th

method

a character string. If "REML" the model is fit by maximizing the restricted log-likelihood. If "ML" the log-likelihood is maximized. Defaults to "REML".

na.action

a function that indicates what should happen when the data contain NAs. The default action (na.fail) causes lme to print an error message and terminate if there are any incomplete observations.

control

a list of control values for the estimation algorithm to replace the default values returned by the function lmeControl. Defaults to an empty list.

model, x

logicals. If TRUE the corresponding components of the fit (the model frame, the model matrices) are returned.

Value

• An lme object.

Details

Many of the options are not yet implemented.

Examples

data(bdf)
fm <- lme(langPOST ~ IQ.ver.cen + avg.IQ.ver.cen, data = bdf,
          random = ~ IQ.ver.cen | schoolNR)
summary(fm)