anova.gls  R Documentation 
When only one fitted model object is present, a data frame with the
numerator degrees of freedom, Fvalues, and Pvalues
for Wald tests for the terms in the model (when Terms
and
L
are NULL
), a combination of model terms (when
Terms
in not NULL
), or linear combinations of the model
coefficients (when L
is not NULL
). Otherwise, when
multiple fitted objects are being compared, a data frame with
the degrees of freedom, the (restricted) loglikelihood, the
Akaike Information Criterion (AIC), and the Bayesian Information
Criterion (BIC) of each object is returned. If test=TRUE
,
whenever two consecutive objects have different number of degrees of
freedom, a likelihood ratio statistic with the associated pvalue is
included in the returned data frame.
## S3 method for class 'gls'
anova(object, ..., test, type, adjustSigma, Terms, L, verbose)
object 
an object inheriting from class 
... 
other optional fitted model objects inheriting from
classes 
test 
an optional logical value controlling whether likelihood
ratio tests should be used to compare the fitted models represented
by 
type 
an optional character string specifying the type of sum of
squares to be used in Ftests for the terms in the model. If

adjustSigma 
an optional logical value. If 
Terms 
an optional integer or character vector specifying which
terms in the model should be jointly tested to be zero using a Wald
Ftest. If given as a character vector, its elements must correspond
to term names; else, if given as an integer vector, its elements must
correspond to the order in which terms are included in the
model. This argument is only used when a single fitted object is
passed to the function. Default is 
L 
an optional numeric vector or array specifying linear
combinations of the coefficients in the model that should be tested
to be zero. If given as an array, its rows define the linear
combinations to be tested. If names are assigned to the vector
elements (array columns), they must correspond to coefficients
names and will be used to map the linear combination(s) to the
coefficients; else, if no names are available, the vector elements
(array columns) are assumed in the same order as the coefficients
appear in the model. This argument is only used when a single fitted
object is passed to the function. Default is 
verbose 
an optional logical value. If 
a data frame inheriting from class "anova.lme"
.
Likelihood comparisons are not meaningful for objects fit using restricted maximum likelihood and with different fixed effects.
JosÃ© Pinheiro and Douglas Bates bates@stat.wisc.edu
Pinheiro, J. C. and Bates, D. M. (2000), MixedEffects Models in S and SPLUS, Springer, New York.
gls
, gnls
, nlme
,
lme
, logLik.gls
,
AIC
, BIC
,
print.anova.lme
# AR(1) errors within each Mare
fm1 < gls(follicles ~ sin(2*pi*Time) + cos(2*pi*Time), Ovary,
correlation = corAR1(form = ~ 1  Mare))
anova(fm1)
# variance changes with a power of the absolute fitted values?
fm2 < update(fm1, weights = varPower())
anova(fm1, fm2)
# Pinheiro and Bates, p. 251252
fm1Orth.gls < gls(distance ~ Sex * I(age  11), Orthodont,
correlation = corSymm(form = ~ 1  Subject),
weights = varIdent(form = ~ 1  age))
fm2Orth.gls < update(fm1Orth.gls,
corr = corCompSymm(form = ~ 1  Subject))
anova(fm1Orth.gls, fm2Orth.gls)
# Pinheiro and Bates, pp. 215215, 255260
#p. 215
fm1Dial.lme <
lme(rate ~(pressure + I(pressure^2) + I(pressure^3) + I(pressure^4))*QB,
Dialyzer, ~ pressure + I(pressure^2))
# p. 216
fm2Dial.lme < update(fm1Dial.lme,
weights = varPower(form = ~ pressure))
# p. 255
fm1Dial.gls < gls(rate ~ (pressure +
I(pressure^2) + I(pressure^3) + I(pressure^4))*QB,
Dialyzer)
fm2Dial.gls < update(fm1Dial.gls,
weights = varPower(form = ~ pressure))
anova(fm1Dial.gls, fm2Dial.gls)
fm3Dial.gls < update(fm2Dial.gls,
corr = corAR1(0.771, form = ~ 1  Subject))
anova(fm2Dial.gls, fm3Dial.gls)
# anova.gls to compare a gls and an lme fit
anova(fm3Dial.gls, fm2Dial.lme, test = FALSE)
# Pinheiro and Bates, pp. 261266
fm1Wheat2 < gls(yield ~ variety  1, Wheat2)
fm3Wheat2 < update(fm1Wheat2,
corr = corRatio(c(12.5, 0.2),
form = ~ latitude + longitude, nugget = TRUE))
# Test a specific contrast
anova(fm3Wheat2, L = c(1, 0, 1))
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