If you assume that the variance is the same in all your subsets, you can do an lm analysis with your subset classification as a factor. You could also analyze the interaction between factors and between factors and your numeric independent variable. You also should consider repeated measurement methods since you are taking 2 cores from the same individuals.
On 9/20/2010 11:46 PM, Oyomoare Osazuwa-Peters wrote: > Please I need some help using R to > analyze my data. What I > would like to do is to repeat the same basic process (e.g. linear regression > between wood density and distance from pith) for at least 240 data > subsets > within the main data-frame. Within the main data-frame, these data subsets > will be defined by three > variables > namely,  species, individual and core (i.e. 20 species, at least 6 > individuals > of each species, and 2 cores from each individual).  Whereas I can write > the code to carry out this process for each subset, I am unable to > successfully > instruct R to automatically carry out the process for each of these > subsets (perhaps using loops). So to illustrate what I have done so far > with the codes > below I was able to run a regression > analysis for core ‘a’ of individual 1 in > the species “Apeime�. But rather than do this 240 times, I would like to > tell R > to repeat the process automatically using loops or any method that > works. > >  > > Code: > >  > > RG2<-BCI[BCI$Species == "APEIME" > & > BCI$Individual == 1 & BCI$Core == "a", ] > >> plot(x=RG2$DP..cm., > y=RG2$WD..g.cm3, > xlab="Distance from pith cm", main="APEIME1a", > ylab="Wood density g/cm3") > >> > RG2lm<-lm(RG2$WD..g.cm3~RG2$DP..cm.) > >> summary(RG2lm) > >  > > Thanks > >  > > Oyomoare > > > > > > [[alternative HTML version deleted]] > > > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.