On Mon, Oct 5, 2009 at 8:52 AM, Umesh Srinivasan <umesh.sriniva...@gmail.com> wrote: > Hi all, [snip] > > Fixed effects: > Estimate Std. Error z value Pr(>|z|) > (Intercept) -138.8423 0.4704 -295.1 < 2e-16 *** > SpeciesCr -0.9977 0.6259 -1.6 0.11091 > SpeciesDb -1.2140 0.6945 -1.7 0.08046 . > SpeciesHk -2.0864 1.2134 -1.7 0.08553 . > SpeciesPa -2.6245 1.2063 -2.2 0.02958 * > SpeciesPs 1.3056 0.4027 3.2 0.00119 ** > distancen 121.7170 0.3609 337.3 < 2e-16 *** > --- > Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > Correlation of Fixed Effects: > (Intr) SpcsCr SpcsDb SpcsHk SpecsP SpcsPs > SpeciesCr -0.423 > SpeciesDb -0.391 0.295 > SpeciesHk -0.223 0.169 0.152 > SpeciesPa -0.222 0.170 0.153 0.088 > SpeciesPs -0.732 0.507 0.458 0.262 0.263 > distancen -0.648 -0.020 -0.002 -0.003 -0.006 0.085 > > Here, clearly, distance from the tree has an effect, but I want to > know whether the identity of the species influences seedling numbers > in general. I am unable, however, to make much sense of the output.
As with other linear model type functions in R the summary method returns tests based on a factor's contrasts (treatment by default, comparing other levels to a baseline level). To get an omnibus test of a factor, one option is to create a model with and without the factor and perform an LRT: library(lme4) example(glmer) gm0 <- glmer(cbind(incidence, size - incidence) ~ 1 + (1 | herd), family = binomial, data = cbpp) anova(gm0, gm1) > Also, what does correlation of fixed effects really tell me? > These can be of interest for inference (e.g. a confidence region for two of the coefficients is an ellipse with eccentricity defined by their correlation). hth, Kingsford > Many thanks for any help. > > Cheers, > Umesh Srinivasan, > Bangalore, India > > ______________________________________________ > R-help@r-project.org 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. > ______________________________________________ R-help@r-project.org 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.
