[R-sig-ME] Start values for glmer: Bug?
Adam D. I. Kramer
adik at ilovebacon.org
Mon Apr 26 20:22:39 CEST 2010
Hello,
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
[[1]]
(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,
start=list(ST=arg,fixef=fe[1:6]))
...and this is the eventual completion, with the warning message I do not
understand:
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...
Advice?
--
Adam D. I. Kramer
Ph.D. Candidate, Psychology
adik at uoregon.edu
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