Thanks for the information! Leaf ======= At 2005-11-06, 11:07:31 you wrote: =======
>IMHO, the details section of help(formula) provides a nicer help. > >Regards, Adai > > >On Sun, 2005-11-06 at 08:27 -0500, John Fox wrote: >> Dear Leaf, >> >> I assume that you're using lm() to fit the model, and that you don't really >> want *all* of the interactions among 20 predictors: You'd need quite a lot >> of data to fit a model with 2^20 terms in it, and might have trouble >> interpreting the results. >> >> If you know which interactions you're looking for, then why not specify them >> directly, as in lm(y ~ x1*x2 + x3*x4*x5 + etc.)? On the other hand, it you >> want to include all interactions, say, up to three-way, and you've put the >> variables in a data frame, then lm(y ~ .^3, data=DataFrame) will do it. >> There are many terms in this model, however, if not quite 2^20. >> >> The introductory manual that comes with R has information on model formulas >> in Section 11. >> >> I hope this helps, >> John >> >> -------------------------------- >> John Fox >> Department of Sociology >> McMaster University >> Hamilton, Ontario >> Canada L8S 4M4 >> 905-525-9140x23604 >> http://socserv.mcmaster.ca/jfox >> -------------------------------- >> >> > -----Original Message----- >> > From: [EMAIL PROTECTED] >> > [mailto:[EMAIL PROTECTED] On Behalf Of Leaf Sun >> > Sent: Sunday, November 06, 2005 3:11 AM >> > To: r-help@stat.math.ethz.ch >> > Subject: [R] OLS variables >> > >> > Dear all, >> > >> > Is there any simple way in R that can I put the all the >> > interactions of the variables in the OLS model? >> > >> > e.g. >> > >> > I have a bunch of variables, x1,x2,.... x20... I expect then >> > to have interaction (e.g. x1*x2, x3*x4*x5... ) with some >> > combinations(2 way or higher dimensions). >> > >> > Is there any way that I can write the model simpler? >> > >> > Thanks! >> > >> > Leaf >> > >> > >> >> ______________________________________________ >> R-help@stat.math.ethz.ch mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html >> >-- >Adaikalavan Ramasamy [EMAIL PROTECTED] >Centre for Statistics in Medicine http://www.ihs.ox.ac.uk/csm/ >Wolfson College Annexe Tel : 01865 284 408 >Linton Road, Oxford OX2 6UD Fax : 01865 284 424 > >. = = = = = = = = = = = = = = = = = = = = Leaf Sun [EMAIL PROTECTED] 2005-11-06
______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html