On Wed, 19 Jan 2005 21:20:22 -0500 K Fernandes wrote: > Hello, > I would like to use lm to model the equation y=x^2. > > However, when I use > > z<-lm(formula=y~x^2) > summary(z) > > I obtain results that are equivalent to when I use > > z<-lm(formula=y~x) > summary(z)
In formulas "^" specifies interactions. "^2" selects all second order interactions from the preceeding term. If you want the arithmetic function "^" you have to insulate the term in I(), i.e., try to fit lm(y ~ I(x^2)) See ?formula for more details. Z > That is, using x instead of x^2. > > However, I do get different results when I use > > z<-lm(formula=y~log(x)) > summary(z) > > Does anyone know why this might be the case? Any ideas are > appreciated. > > Thank you, > K > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
