[R-sig-ME] Maximum nAGQ=25?

[Ben Bolker]

Ben Bolker <bbolker at ...> writes:

> 
> Ross Boylan <ross <at> ...> writes:
> 
> > On Thu, Sep 26, 2013 at 04:23:47PM +0000, Ben Bolker wrote:
> > > Rafael Sauter <rafael.sauter <at> ...> writes:
> 
>  [snip]
> 
> > > > As I did not find any discussion about this change in the new
> > > > lme4-version let me allow to ask:
> > > > 
> > > > 1) Why is 25 a reasonable upper bound for nAGQ? 
> What were the reasons to
> > > > implement this upper bound? Is the increasing
>  complexity as mentioned in
> > > > the details of '?glmer' the the main reason for this?
> > > > 
> 
  [snip]
 
> > If the limit is hard-coded to 25, it will be hard to discover if using
> > >25 matters.  That seems to me an argument for not hard coding it.  I
> > suppose if the results had not stabilized by 25 that would be an
> > indication.
> > 
> > OTOH, 25 is a lot of quadrature points.
> > 

  OK, Doug Bates has chimed in at 

https://github.com/lme4/lme4/issues/136

to point out that the current implementation of AGHQ is table-driven
(see https://github.com/lme4/lme4/blob/master/R/GHrule.R ); thus,
the decision to limit the number of quadrature points is *not*
arbitrary, and extending it is not just a matter of removing
the test for nAGQ>25.  The table could be extended, or a new implementation
could compute the table on the fly -- but for now this will probably
go back down the priority list a bit unless someone demonstrates
a really pressing need or sends us a pull request ...

  Ben Bolker