Hi Bert Gunter <gunter.ber...@gene.com> napsal dne 14.04.2010 18:54:37:
> > > Petr Pikal wrote: > > "... > > I mean that you can use > > fit<- lm(y~x+I(x^2)) > coef(fit)[1] + coef(fit)[2]*x + coef(fit)[3]*x^2 > > but you can not use > > fit<- lm(y~poly(x,2)) > coef(fit)[1] + coef(fit)[2]*x + coef(fit)[3]*x^2 " > > (to get the fits for any x vector) > > -- But you **can** use > > ypred <- predict(fit,data.frame(x = x)) > > -- in **both** cases. Which is, I think, how it should be done. I completely agree with you. However sometimes it is necessary to put an equation and estimated coefficients to a report - for that you can not use coefficients from poly() estimate directly. (Please do not beat me, I know that polynomial model is ***rarely*** physically viable and personally I never use it until it it has not a physical sense - like free fall) Regards Petr > > Cheers, > Bert > > Bert Gunter > Genentech Nonclinical Statistics > > > > > answer is, "yes you can." See ?SafePrediction for details. -- Bert > > > > Regards > > Petr > > > > > > > > Thanks in advance, > > > Stefan > > > > > > ______________________________________________ > > > 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. > > > > ______________________________________________ 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.