[R-sig-ME] lmer (binomial) and mcmcsamp

[Dieter Menne]

Douglas,

I am using the latest CRAN version; details see below.

I tried to run mcmcsamp on a problem of the form 

The model is

 lmer(RespB~Treat+Gender+(1|Pat),family=binomial) 


Results look ok, in reasonable agreement with method="PQL", and in good
agreement with Göran's glmmML.

Running mcmcsamp() gave strange results. See 

http://www.menne-biomed.de/uni/mcmc20000.pdf
http://www.menne-biomed.de/uni/mcmc2000.pdf

I cannot get rid of the occasional stuck flat segments in between, even if I run
several times. Is this

-- Expected behavior, do your homework
-- Somewhat fishy; don't trust the results
-- Ill posed problem
-- Well known issue with current lmer
-- ...

Dieter

#------------------------------
Generalized linear mixed model fit using Laplace 
Formula: form 
   Data: x 
 Family: binomial(logit link)
 AIC BIC logLik deviance
 340 356   -166      332
Random effects:
 Groups Name        Variance Std.Dev.
 Pat    (Intercept) 2.15     1.47    
number of obs: 426, groups: Pat, 20

Estimated scale (compare to  1 )  0.859 

Fixed effects:
            Estimate Std. Error z value Pr(>|z|)    
(Intercept)   -1.809      0.497   -3.64  0.00027 ***
TreatFOS      -0.267      0.290   -0.92  0.35775    
Genderm       -0.775      0.778   -0.99  0.31975    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Correlation of Fixed Effects:
         (Intr) TrtFOS
TreatFOS -0.274       
Genderm  -0.593  0.009


Package: lme4
Version: 0.99875-9
Date: 2007-10-14
Built: R 2.6.0; i386-pc-mingw32; 2007-10-15 12:22:16; windows