[R] Getting the groupmean for each person

[Gabor Grothendieck]

predict(lm(AV~as.factor(GROUP)))



Felix Eschenburg <Atropin75 <at> t-online.de> writes:

: 
: Hello list !
: 
: I have a huge data.frame with several variables observed on about 3000 
: persons. For every person (row) there is variable called GROUP which indices 
: the group the person belongs to. There is also another variable AV for each 
: person. Now i want to create a new variable which holds the group mean of AV 
: as a value for each person.
: With tapply(AV,GROUP,mean) i get the means for each level of GROUP, but i 
: cannot find out, how to give every person the groupmean as a value (every 
: person should have the same value as every other person in the same group). 
: 
: Has anybody any ideas how to do that ?
: 
: Yours sincerly
: Felix Eschenburg