Re: [R] Using lm to estimate a parameter?
Uwe Ligges statistik.tu-dortmund.de> writes: > > On 19.02.2013 11:23, hellen wrote: > > Hi, > > I have a data with three variables (X,Y,Z) and I have an equation as > > Z=X/(1+L*X/Y) where L is a constant which need to be estimated from data. > > How should I write the formula in lm or is it possible to fit a linear > > model in this case? > > Neither, it is nonlinear in the parameters. See ?nls or ?optim, for example. Well, if the Z values are not too small, you can linearize it as U = (X Y - Y Z) / Z = L X and solve it with lm(U ~ X - 1), that is without absolute term. > Uwe Ligges > > > > > Thanks! > > Hallen > > > __ 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.
Re: [R] Using lm to estimate a parameter?
On 19.02.2013 11:23, hellen wrote: Hi, I have a data with three variables (X,Y,Z) and I have an equation as Z=X/(1+L*X/Y) where L is a constant which need to be estimated from data. How should I write the formula in lm or is it possible to fit a linear model in this case? Neither, it is nonlinear in the parameters. See ?nls or ?optim, for example. Uwe Ligges Thanks! Hallen [[alternative HTML version deleted]] __ 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] Using lm to estimate a parameter?
Hi, I have a data with three variables (X,Y,Z) and I have an equation as Z=X/(1+L*X/Y) where L is a constant which need to be estimated from data. How should I write the formula in lm or is it possible to fit a linear model in this case? Thanks! Hallen [[alternative HTML version deleted]] __ 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.
