I'm using lmer to fit mixed-effect logistic regression models. This 
is for a small data set.

First, I fit a constant:

Generalized linear mixed model fit using Laplace
Formula: propm ~ (1 | study)
    Data: inducedSR71507.dat
  Family: binomial(logit link)
    AIC   BIC logLik deviance
  183.7 189.4 -89.84    179.7
Random effects:
  Groups Name        Variance Std.Dev.
  study  (Intercept) 0.035812 0.18924
number of obs: 127, groups: study, 21

Estimated scale (compare to  1 )  1.028571

Fixed effects:
             Estimate Std. Error z value Pr(>|z|) 
(Intercept)  0.11256    0.04979   2.261   0.0238 *
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

So far, so good.

Next, I fit a model with a fixed effect:

Generalized linear mixed model fit using Laplace
Formula: propm ~ 1 + c.age + (1 | study)
    Data: inducedSR71507.dat
  Family: binomial(logit link)
   AIC  BIC logLik deviance
  5339 5348  -2667     5333
Random effects:
  Groups Name        Variance Std.Dev.
  study  (Intercept) 0.44094  0.66404
number of obs: 127, groups: study, 21

Estimated scale (compare to  1 )  314587114

Fixed effects:
             Estimate Std. Error z value Pr(>|z|)
(Intercept) 0.058093   1.033273 0.05622    0.955
c.age       0.007262   0.095393 0.07613    0.939

That is one heck of a large scale parameter!

I would be glad to be shown what I am doing wrong, but I am thinking 
that this is a bug......

study is entered as a factor in the data frame.

here is the session info

>  sessionInfo()
R version 2.5.1 (2007-06-27)
i386-apple-darwin8.9.1

locale:
en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] "stats4"    "stats"     "graphics"  "grDevices" "utils" 
"datasets"  "methods"   "base"    

other attached packages:
       mlmRev         lme4         MASS       Matrix      lattice         nlme
    "0.995-1"  "0.99875-4"     "7.2-34" "0.999375-0"    "0.15-11"     "3.1-83"


Any and all help is very much appreciated!


-- 
Steven Orzack

The Fresh Pond Research Institute
173 Harvey Street
Cambridge, MA. 02140
617 864-4307

www.freshpond.org
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