Akaike information criterion of a tree. If no such values are
available, \code{NULL} is returned.
- \code{anova} is another generic function that is used to compare
+ \code{anova} is another generic function which is used to compare
nested models: the significance of the additional parameter(s) is
tested with likelihood ratio tests. You must ensure that the models
are effectively nested (if they are not, the results will be