[R] lmer- why do AIC, BIC, loglik change?

[Darren M. Ward]

Hi all,

I am having issues comparing models with lmer.  As an example, when
 I run the code below the model summaries (AIC, BIC, loglik) differ between 
the summary() and anova() commands.  Can anyone clear up what's wrong?

Thank you!

Darren Ward

library(lme4)
data(sleepstudy)
fm1<-lmer(Reaction ~ Days + (1|Subject), sleepstudy)
summary(fm1)
fm2<-lmer(Reaction ~ Days + (Days|Subject), sleepstudy)
summary(fm2)
anova(fm1, fm2)

Sample output:

> summary(fm1)
Linear mixed-effects model fit by REML 
Formula: Reaction ~ Days + (1 | Subject) 
   Data: sleepstudy 
  AIC  BIC logLik MLdeviance REMLdeviance
 1792 1802 -893.2       1794         1786

> summary(fm2)
Linear mixed-effects model fit by REML 
Formula: Reaction ~ Days + (Days | Subject) 
   Data: sleepstudy 
  AIC  BIC logLik MLdeviance REMLdeviance
 1754 1770 -871.8       1752         1744

> anova(fm1, fm2)
Data: sleepstudy
Models:
fm1: Reaction ~ Days + (1 | Subject)
fm2: Reaction ~ Days + (Days | Subject)
    Df     AIC     BIC  logLik  Chisq Chi Df Pr(>Chisq)    
fm1  3 1800.10 1809.68 -897.05                             
fm2  5 1761.98 1777.95 -875.99 42.115      2  7.158e-10 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 
> sessionInfo()
R version 2.4.0 (2006-10-03) 
i386-pc-mingw32 

locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

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

other attached packages:
     vegan       lme4     Matrix    lattice 
   "1.8-3" "0.9975-6" "0.9975-3"   "0.14-9"