[R-sig-ME] lmer, poisson family and mcmcsamp
Amelie LESCROEL
lescroel at cebc.cnrs.fr
Mon Feb 16 16:59:53 CET 2009
Dear all,
Could someone explain to me why summary(lmer.object) is giving z values
and Pr(>|z|) when the lmer.object was fitted with family=poisson? I used
to fit linear mixed models with family=gaussian and link="identity" or
link="log", then used mcmcsamp() and HPDinterval() for computing
"confidence" intervals and considered that a fixed effect was
significant when the 95% HPD interval did not include zero. Now, with
family=poisson, when I use mcmcsamp(), I get the following:
> set.seed(101); mcmcfm1 <- mcmcsamp(fm1, n=10000)
Error in .local(object, n, verbose, ...) : Update not yet written
but I get z values and Pr(>|z|). Why is it so? Can we "trust" this
probability for judging of the fixed effects significance? Would the
mcmcsamp method be available soon for families other than gaussian?
Thanks in advance,
Amélie
PS: When will lme4_1.0 be released? Many thanks to Douglas Bates for
developing lme4 in interaction with users, and for sharing it. Please
don't give up on making it available in R. lme4 is a wonderful tool
which is helping me understanding penguin's foraging behaviour (and
advanced stats!) as it is helping others in plant ecology or human
psychology.
> sessionInfo()
R version 2.7.2 (2008-08-25)
i386-pc-mingw32
locale:
LC_COLLATE=French_France.1252;LC_CTYPE=French_France.1252;LC_MONETARY=French_France.1252;LC_NUMERIC=C;LC_TIME=French_France.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] lme4_0.999375-28 Matrix_0.999375-17 lattice_0.17-17
gdata_2.4.2
loaded via a namespace (and not attached):
[1] grid_2.7.2 gtools_2.5.0 tools_2.7.2
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