Noobie question, regression across levels
Much thanks! This helped a lot. Another quick one: In using the lmList function in the nlme package, is it possible to subset my data according to the number of observations in each level? (ie. I obviously want to include only those levels in which the observations are of sufficient size for regression). What is the best way to exclude factors of insufficient size? Can I do it inside the lmList function? I've read the requisite help files etc. and two hours later am still confused. Thanks in advance, Allen
Ben Bolker wrote:
RichardLang wrote:
I've just started using R last week and am still scratching my head. I have a data set and want to run a separate regression across each level of a factor (treating each one separately). The data right now is arranged such that the value of the factor along which I want to "split" my data is one column among many. Best way to do this? Thanks!
You can check out lmList function in the nlme package, or more crudely:
lmfun <- function(d) { lm(y~x,data=d) }
myLmList <- lapply(split(mydata,splitfactor),lmfun)
even more compactly/confusingly:
myLmList <- lapply(split(mydata,splitfactor),lm,formula=y~x)
good luck
Ben Bolker
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