Ahmed Attia
2013-Jan-12 23:30 UTC
[R] Getting the R squared value in asymptotic regression model
Please help getting the R squared value in asymptotic regression model I use the code below model1<-nls(GN1~SSasymp (nrate,a,b,c), data = data.1 ) and R produced the modell coefficients without the R squared value? -- Ahmed M. Attia Research Assistant Dept. Of Soil&Crop Sciences Texas A&M University ahmed <ahmedatia@zu.edu.eg>.attia@ag.tamu.edu Cell phone: 001-979-248-5215 [[alternative HTML version deleted]]
David Winsemius
2013-Jan-13 00:34 UTC
[R] Getting the R squared value in asymptotic regression model
On Jan 12, 2013, at 3:30 PM, Ahmed Attia wrote:> Please help getting the R squared value in asymptotic regression model > > I use the code below > > model1<-nls(GN1~SSasymp (nrate,a,b,c), data = data.1 ) > > and R produced the modell coefficients without the R squared value?What makes you think there should be an R^2 value? From the archives: https://stat.ethz.ch/pipermail/r-help/2002-July/023461.html http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892436/ From the background section to that article: "Although it is known now for some time that R2 is an inadequate measure for nonlinear regression, many scientists and also reviewers insist on it being supplied in papers dealing with nonlinear data analysis. Several initial and older descriptions for R2 being of no avail in nonlinear fitting had pointed out this issue but have probably fallen into oblivion [2-8]. This observation might be due to differences in the mathematical background of trained statisticians and biochemists/pharmacologists who often apply statistical methods but lack detailed statistical insight." -- David Winsemius, MD Alameda, CA, USA
David Winsemius
2013-Jan-13 01:26 UTC
[R] Getting the R squared value in asymptotic regression model
On Jan 12, 2013, at 5:04 PM, Ahmed Attia wrote:> So what is the best method to test the goodness of fit in nonlinear > models?Did you read the citation offered? -- David.> > On Sat, Jan 12, 2013 at 4:34 PM, David Winsemius <dwinsemius@comcast.net > > wrote: > > On Jan 12, 2013, at 3:30 PM, Ahmed Attia wrote: > > Please help getting the R squared value in asymptotic regression model > > I use the code below > > model1<-nls(GN1~SSasymp (nrate,a,b,c), data = data.1 ) > > and R produced the modell coefficients without the R squared value? > > What makes you think there should be an R^2 value? > > From the archives: > https://stat.ethz.ch/pipermail/r-help/2002-July/023461.html > > http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892436/ > > From the background section to that article: > > "Although it is known now for some time that R2 is an inadequate > measure for nonlinear regression, many scientists and also reviewers > insist on it being supplied in papers dealing with nonlinear data > analysis. Several initial and older descriptions for R2 being of no > avail in nonlinear fitting had pointed out this issue but have > probably fallen into oblivion [2-8]. This observation might be due > to differences in the mathematical background of trained > statisticians and biochemists/pharmacologists who often apply > statistical methods but lack detailed statistical insight." > > -- > > David Winsemius, MD > Alameda, CA, USA > > > > > -- > Ahmed M. Attia > > > Research Assistant > Dept. Of Soil&Crop Sciences > Texas A&M University > ahmed.attia@ag.tamu.edu > Cell phone: 001-979-248-5215 >David Winsemius, MD Alameda, CA, USA [[alternative HTML version deleted]]