On Sun, Jul 27, 2008 at 4:19 AM, Mark Difford <[EMAIL PROTECTED]> wrote: > > Hi Jinsong and Thierry, > >>> (x1 + x2 + x3) ^2 will give you the main effects and the interactions. > > Although it wasn't specifically requested it is perhaps important to note > that (...)^2 doesn't expand to give _all_ interaction terms, only > interactions to the second order, so the interaction term x1:x2:x3 will be > missing, To get these, do > > (x1 + x2 + x3)^3
Or just x1 * x2 * x3 Hadley -- http://had.co.nz/ ______________________________________________ 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.
