[R] Mixed models and missing p-value...

[Christoph Buser]

Dear Simon

There was a discussion about degrees of freedom in linear mixed
models on the R-list last week. Have a look at

https://stat.ethz.ch/pipermail/r-help/2006-January/085560.html

and following. There have been earlier discussions about that
topic. Try also:

RSiteSearch("degree freedom mixed")


Regards,

Christoph Buser

--------------------------------------------------------------
Christoph Buser <buser at stat.math.ethz.ch>
Seminar fuer Statistik, LEO C13
ETH (Federal Inst. Technology)	8092 Zurich	 SWITZERLAND
phone: x-41-44-632-4673		fax: 632-1228
http://stat.ethz.ch/~buser/
--------------------------------------------------------------


Simon Blanchet writes:
 > Dear R-users,
 > 
 > I computed a simple mixed models which was:
 > 
 >          mod<-lmer(nb ~ site + (1|patelle),tr)
 > 
 > The output was:
 > 
 > Linear mixed-effects model fit by REML
 > Formula: nb ~ site + (1 | patelle)
 >     Data: tr
 >        AIC      BIC    logLik MLdeviance REMLdeviance
 >   1157.437 1168.686 -574.7184   1164.523     1149.437
 > Random effects:
 >   Groups   Name        Variance Std.Dev.
 >   patelle  (Intercept)  34.995   5.9157
 >   Residual             744.736  27.2899
 > # of obs: 123, groups: patelle, 33
 > 
 > Fixed effects:
 >              Estimate Std. Error t value
 > (Intercept)  60.3483     4.3929 13.7378
 > siteLCN     -20.1969     7.8070 -2.5870
 > siteLCS     -18.2154     6.1514 -2.9612
 > 
 > Correlation of Fixed Effects:
 >          (Intr) sitLCN
 > siteLCN -0.563
 > siteLCS -0.714  0.402
 > 
 > I don't understand why D.F. and p-values associated to the fixed-effects 
 > coefficients are missing.
 > Could anyone help me?
 > 
 > When I tried another model (mod2<-lmer(nb ~ site + 
 > (1|patelle),tr,family=poisson)), D.F. and p-values were given...
 > 
 > Thank you in advance.
 > 
 > Very sincerely, Simon
 > 
 > 
 > 
 > BLANCHET Simon
 > PhD student
 > Université Laval - Québec-Océan / CIRSA
 > Pavillon Alexandre-Vachon
 > Local 8022
 > Québec (Québec), Canada G1K 7P4
 > Téléphone : (418) 656-2131 poste 8022
 > courriel : simon.blanchet at giroq.ulaval.ca
 > 
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