PS, the equivalent for a glm is: > sum.modeltest <- summary(modeltest) > sum.modeltest$dispersion
Hope this helps. On 11/09/06, Toby Gardner <[EMAIL PROTECTED]> wrote: > Dear list, > > I am needing to extract the estimate of overdispersion (deviance / residual > degrees of freedom or c-hat) from multiple model objects - so they can then > be used to compare the extent of overdispersion among alternative models as > well as calculate qausi-AIC values. I have been unable to do this, despite > consulting a number of manuals and searching the R-help. I am imaging that > in theory it should be possible with some call to attr(), but i have so far > had no success. > > An example model output would be: > > > modeltest<-lmer(Coleodactylus_amazonicus_N~USD + > > (1|site),data=SFArray,family=poisson,method="Laplace",control=list(usePQL=FALSE, > > msVerbose=TRUE)) > > summary(modeltest) > > ------------ > > Generalized linear mixed model fit using Laplace > Formula: Coleodactylus_amazonicus_N ~ USD + (1 | site) > Data: SFArray > Family: poisson(log link) > AIC BIC logLik deviance > 75.94996 81.68603 -34.97498 69.94996 > Random effects: > Groups Name Variance Std.Dev. > site (Intercept) 2.6076 1.6148 > number of obs: 50, groups: site, 5 > > Estimated scale (compare to 1) 1.080798 > > ------------ > > What I need is to extract this value (1.080798) from multiple lmer objects. > Has anyone any recommendations? I also need to do this for glm objects > although I suspect if someone was able to kindly point me in the right > direction then the solution is likely to be similar. > > Very many thanks, > > Toby Gardner > > > sessionInfo() > Version 2.3.1 (2006-06-01) > i386-pc-mingw32 > > attached base packages: > [1] "datasets" "graphics" "grDevices" "methods" "stats" "utils" > "base" > > other attached packages: > JGR iplots JavaGD lme4 Matrix lattice MASS > rJava > "1.4-7" "1.0-3" "0.3-4" "0.995-2" "0.995-15" "0.13-8" "7.2-27.1" > "0.4-6" > > > School of Environmental Sciences > University of East Anglia > Norwich, NR4 7TJ > United Kingdom > Email: [EMAIL PROTECTED] > Website: www.uea.ac.uk/~e387495 > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- ================================= David Barron Said Business School University of Oxford Park End Street Oxford OX1 1HP ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
