Rolf Turner <rolf.turner <at> xtra.co.nz> writes: > > On 21/08/13 11:23, Ye Lin wrote: > > T > > hanks for your insights Rolf! The model I want to fit is y=x/a+x with > > no intercept, so I transformed it to 1/y=1+a/x as they are the same. > > For crying out loud, they are ***NOT*** the same. The equations y = > x/(a+x) and > 1/y = 1 + a/x are indeed algebraically identical, but if an "error" or > "noise" term is added > to each then then the nature of the error term is vastly different. It > is the error or > noise term that is of central concern in a statistical context. > > cheers, > > Rolf
For what it's worth this model can also be fitted (without messing up the error structure) via glm(1/y~x,family=gaussian(link="inverse")) Although you may not get the parameters in exactly the form you want. ______________________________________________ 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.
