[R] lme questions

[Christian Hennig]

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

Where can I get an estimator for the variance of the random factor fMub?

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"

(plot(logpepcr0) works; I use R 1.3.0 on Solaris.)

Thank you for help.
Christian

***********************************************************************
Christian Hennig
University of Hamburg, Faculty of Mathematics - SPST/ZMS
 (Schwerpunkt Mathematische Statistik und Stochastische Prozesse,
 Zentrum fuer Modellierung und Simulation)
Bundesstrasse 55, D-20146 Hamburg, Germany
Tel: x40/42838 4907, privat x40/631 62 79
hennig at math.uni-hamburg.de, http://www.math.uni-hamburg.de/home/hennig/
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ich empfehle www.boag.de


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