REMLRT.asreml {asremlPlus}  R Documentation 
Extracts the REML log likelhood and the number of variance
parameters from two asreml
objects. It assumes that that the
first asreml
object corresponds to the null hypothesis and
the second asreml
object to the alternative hypothesis for the
test being conducted. That is, the second
asreml
object is the result of fitting a model that is a
reduced version of the model for the first object. In the case
where the reduced model is obtained by setting positivelyconstrained
variance parameters in the full model to zero, the positive.zero
argument should be set to TRUE
so that
the pvalue is computed using a mixture of chisquare distributions as
described in Self and Liang (1987).
The function checks that the models do not differ in either their fixed or sparse models.
## S3 method for class 'asreml' REMLRT(h0.asreml.obj, h1.asreml.obj, positive.zero = FALSE, bound.test.parameters = "none", DF = NULL, bound.exclusions = c("F","B","S","C"), ...)
h0.asreml.obj 

h1.asreml.obj 

positive.zero 
Indicates whether the hypothesized values for the
variance components being tested are on the boundary
of the parameter space. For example, this is true
for positivelyconstrained variance components that,
under the reduced model, are zero. This argument does
not need to be set if 
bound.test.parameters 
Indicates whether for the variance components
being tested, at least some of the hypothesized values
are on the boundary of the parameter space.
The possibilities are 
DF 
A 
bound.exclusions 
A 
... 
Provision for passsing arguments to functions called internally  not used at present. 
A data.frame
containing the log of the likelihood ratio, its degrees of
freedom, its pvalue and the number of bound parameters in each of the two models
being compared.
If DF
is not NULL
, the supplied value is used. Otherwise DF
is determined from the information in h1.asreml.obj
and
h0.asreml.obj
. In this case, the degrees of freedom for the test
are computed as the difference between the two models in the number of variance
parameters whose estimates do not have a code for bound
specified in
bound.exclusions
.
If ASRemlR version 4 is being used then the codes specified in bound.exclusions
are
not restricted to a subset of the default codes, but a warning is issued if a code other
than these is specified.
For ASRemlR version 3, only a subset of the default codes are allowed:
F
(Fixed
), B
(Boundary
), C
(Constrained
) and
S
(Singular
).
The test statistic is calculated as 2(log(REML)_1  log(REML)_0).
This procedure is only approriate when the null hypothesis is that (i) all parameters are on the boundary of the parameter space (ii) all parameters are in the interior of the parameter space, or (iii) there are two parameters, one of which is on the boundary and the other is not. Other cases have been discussed by Self and Liang (1987), but are not implemented here.
Chris Brien
Self, S.G., and Liang, KY. (1987) Asymptotic Properties of Maximum Likelihood Estimators and Likelihood Ratio Tests Under Nonstandard Conditions. Journal of the American Statistical Association, 82, 60510.
infoCriteria.asreml
, testranfix.asrtests
## Not run: REMLRT(ICV.max, ICV.red, bound.test.parameters = "onlybound") ## End(Not run)