[R-sig-ME] Why does anova.merMod use refit?

[Ben Bolker]

Ben Bolker <bbolker at ...> writes:

>   I think there are some reasonable design considerations here,
> not obvious what the best answer(s) is/are.
> 
> 1. one way or the other we should prevent users from running
> anova() on REML-fitted models *with different fixed effects* (arguably
> there is a sensible use case for using anova() on models that
> differ only in their random effects
>   1a. should we try to do this automatically or should we throw
> an error and hint to them how best to achieve their goal?
> 
> 2 refit should allow appropriate optimization control parameters to be set
>   2a a model refit should always inherit the optimization control parameters
> from its parent model
> 
> 3 we should try not to make too many backward-incompatible changes
> (i.e. even if the current behaviour is weird we should make changes
> carefully/gradually so as not to disturb users who have adapted to it)
> 

  [snip snip snip]

  PS: I think opening an issue at http://github.com/lme4/lme4/issues
would be appropriate -- you can briefly summarize/refer to this discussion.
(I might add one myself, but someone else might get around to it first.)