`alrtest`

is a helper function to simulate the functions `lmtest::waldtest()`

and `lmtest::lrtest()`

for adjusted `chantrics`

objects. The method can be
employed to compare nested models (see details).

alrtest(object, ...)

object | a |
---|---|

... | further object specifications (see details), as well as named
parameters that will be passed to |

An object of class `"anova"`

inheriting from class `"data.frame"`

.
The columns are as follows:

The residual number of degrees of freedom in the model.

The increase in residual degrees of freedom with respect to the model in the row above.

The adjusted likelihood ratio statistic.

The p-value of the test that the model above is a "significantly better" model as the one in the current row.

This function is a helper function that creates an interface to
`anova.chantrics()`

that is similar to `lmtest::waldtest()`

and
`lmtest::lrtest()`

.

The standard method is to compare the fitted model object `object`

with the
models in `...`

. Instead of passing the fitted models into `...`

, other
specifications are possible. Note that the types of specifications cannot be
mixed, except between numerics/characters. The type of the second object
supplied determines the algorithm used.

: When supplying two or more`"chantrics"`

objects`"chantrics"`

objects, they will be sorted as in`anova.chantrics()`

. Then, the ALRTS will be computed consecutively between the two neighbouring models. Note that all models must be nested. For details refer to`anova.chantrics()`

.: If the second object is`"numeric"`

`"numeric"`

or`"character"`

, then`"numeric"`

objects corresponding element in`attr(terms(object1), "term.labels")`

will be turned into their corresponding`"character"`

element and will be handled as in`"character"`

below.: If the second object is`"character"`

`"numeric"`

or`"character"`

, then the`"character"`

objects are consecutively included in an update formula like`update(object1, . ~ . - object2)`

: If the second object is a`"formula"`

`"formula"`

, then the second model will be computed as`update(object1, object2)`

.

Then, the adjusted likelihood ratio test statistic (ALRTS), as described in
Section 3.5 of Chandler and Bate
(2007), is computed by
`anova.chantrics()`

.

If a single unnamed object is passed in `...`

, sequential ANOVA is
performed on `object`

.

R. E. Chandler and S. Bate, Inference for clustered data using the independence loglikelihood, Biometrika, 94 (2007), pp. 167–183. doi: 10.1093/biomet/asm015 .

`anova.chantrics()`

for the implementation of the computations of
the test statistics.

`lmtest::waldtest()`

and `lmtest::lrtest()`

for syntax.