[R] Re gression for loop test HELP! URGENT!

[Rbeginner]

Thanks for the suggestion, but I think I might not have made myself very
clear. I actually have about 2000 sets of M, D, O, and S, so it's probably
not efficient to make each a separate set and then index. I've put
everything into a data frame, so I would like to test how well the
regression fit for each group, which consists of 5 sets of M, D, O, and S.
Since I'll need to test it for about 400 groups, I thought a for loop might
be necessary. 
Any suggestions? I'm just not especially sure how to do the for loop.



Daniel Malter wrote:
> 
> for a beginner, it's probably even easier to it by hand if it is just five
> datasets.
> 
> bind the 5 datasets together in one dataset and create and index variable
> (1
> to 5) for each of the observations according to the dataset the
> obersvation
> comes from
> 
> then run five regressions using
> 
> reg1=lm(M~D+O+S,subset=c(index==1))
> .
> .
> .
> reg5=lm(M~D+O+S,subset=c(index==5))
> 
> and then predict from each regression
> 
> predict(reg1,newdata=data.frame(D,O,S))
> .
> .
> .
> predict(reg5,newdata=data.frame(D,O,S))
> 
> You can then assess how well the prediction from each of the datasets fits
> the respective other datasets...
> 
> Daniel
> 
> -------------------------
> cuncta stricte discussurus
> -------------------------
> 
> -----Ursprüngliche Nachricht-----
> Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
> Auftrag von Rbeginner
> Gesendet: Sunday, July 19, 2009 9:49 PM
> An: r-help at r-project.org
> Betreff: [R] Re gression for loop test HELP! URGENT!
> 
> 
> Hi everyone!
> I'm new to R, and I'm stuck on a problem I don't know how to approach.
> I have calculated a regression in the form of M ~ D + O + S, and I would
> like to take this regression and test it with other samples, 5 at a time(5
> meaning 5 set, each consisting M, D, O, and S of a specific date). I
> assume
> I'll need a for loop. Right now, My data of M, D, O, and S are all stored
> in
> separate txt files, but should I just put them into a table or something?
> And then how would I calculate the error of how well the test samples fit
> the original regression?
> This is for my internship, so it's very urgent.
> THANKS A LOT!!!!!
> RBeginner
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