lme questions
On Wed, 29 Aug 2001, Christian Hennig wrote:
Dear list, the following should fit the model log(PEPC.Wert)=fKTemp+fHerk+interaction(fKTemp,fHerk)+fMub+error, where fKTemp, fHerk are fixed effect factors and fMub is a random effects factor nested in fHerk (values are different fopr different values of fHerk).
logpepcr1 <- lme(log(PEPC.Wert) ~ fKTemp*fHerk, random= ~ 1 | fMub, na.action=na.omit)
The following should be without the random factor:
logpepcr0 <- lme(log(PEPC.Wert) ~ fKTemp*fHerk,na.action=na.omit)
Error in getGroups.data.frame(dataMix, groups) : Invalid formula for groups OK, I try with lm:
logpepcr0 <- lm(log(PEPC.Wert) ~ fKTemp*fHerk,na.action=na.omit)
...works. Is the following correct for testing the significance of the random factor?
anova.lme(logpepcr0,logpepcr1)
Model df AIC BIC logLik Test L.Ratio p-value logpepcr0 1 10 3977.354 4030.318 -1978.677 logpepcr1 2 11 3885.392 3943.653 -1931.696 1 vs 2 93.96144 <.0001
No. You need to fit the lme model by maximum likelihood, not the default REML, to be comparable with the lm fit.
Where can I get an estimator for the variance of the random factor fMub?
The standard error is in the summary() output.
Is there a way to specify an interaction between fMub and fKTemp? And why does this happen?
plot(logpepcr1)
Error in do.call(plotFun, as.list(args)) : couldn't find function "xyplot"
That's a legacy of the S origins: xyplot is in package lattice in the Devel section on CRAN (needs grid too) and I don't know if it yet suffices for plot.lme.
(plot(logpepcr0) works; I use R 1.3.0 on Solaris.)
That's using plot.lm.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._