Looping through different groups of variables in models

Hi Kai,
Perhaps something like this:

kmdf<-data.frame(group=rep(c("exp","cont"),each=50),
 time=factor(rep(1:5,20)),
 condition=rep(rep(c("hot","cold"),each=25),2),
 value=sample(100:200,100))
for(timeindx in levels(kmdf$time)) {
 for(condindx in levels(kmdf$condition)) {
  cat("Time",timeindx,"Condition",condindx,"\n")
  subdat<-kmdf[kmdf$time == timeindx & kmdf$condition == condindx,]
  fit<-lm(value~group,subdat)
  print(summary(fit))
  plot(subdat$group,subdat$value)
  by(subdat$value,subdat$group,mean)
 }
}

Getting elegant output is another matter. Have a look at packages
meant to produce fancier R output.

Jim