[R-sig-ME] Start values for glmer: Bug?

Adam D. I. Kramer adik at ilovebacon.org
Mon Apr 26 20:22:39 CEST 2010


 	I'm fitting a model something like this:

s1d2.s <- glmer(chosen ~ rating + option + option2 + rating:option +
rating:option2 + (distNum|studyID), data=cc2, family=binomial)

...pretty straightforward. Of course, it doesn't converge...boo. So I turn
on verbose, and see that it's starting with some really improbable values. 
So I plug in some start values from other similar matrices that fit and some
good guesses, and it chugs along and finishes, but gives me a warning I do
not understand.

These are my start values:

> arg
             (Intercept) distNum
(Intercept)         1.9     0.0
distNum            -0.1     0.5

> fe
    (Intercept)         rating         option        option2  rating:option
        -7.5000         1.1000        -0.3000         0.0090         0.0500 
rating:option2        distNum     condition1     condition2
        -0.0025         0.2000         0.1000         0.1000

...this is my call:
s1d2.s <- glmer(chosen ~ rating + option + option2 + rating:option +
rating:option2 + (distNum|studyID), data=cc2, family=binomial, verbose=TRUE,

...and this is the eventual completion, with the warning message I do not

  65:     1633.7847:  2.71240 0.719770 -0.228343 -8.32184  1.56395 -0.0683526
0.00144433 0.0226594 -0.000315729
Warning message:
In sort(names(start)) == sort(names(FL)) :
   longer object length is not a multiple of shorter object length

...the first-round verbose output does indeed use my provided start values,
in the right order. The summary table, eventually, also uses names(fe)
instead of the actual variable names passed to glmer...which I would argue
is inappropriate behavior. But it's the problem with the length of the names
of `start` that has me confused.

The help page says that I should be passing a list with items ST and fixef,
and I'm doing that, and it's working...


Adam D. I. Kramer
Ph.D. Candidate, Psychology
adik at uoregon.edu

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