I suggest you consult a local statistician. You could also post to a statistical help list like stats.stackexchange.com. Your query has nothing to do with R, but is rather about the meaningfulness (or lack thereof) of statistical significance in nonlinear modeling.
-- Bert On Tue, Jun 5, 2012 at 6:49 AM, Nerak <nera...@hotmail.com> wrote: > Hi all, > I'm struggling with nls. How do you know if your model is significant? For a > lm, you get a p-value, but you don't get it for a nls. Is there a way to > calculate it? > > For a lm I use this: > a<-summary(lm(model ~obs)) > f.stat<-a$fstatistic > p.value<-1-pf(f.stat["value"],f.stat["numdf"],f.stat["dendf"]) > > Is there something similar for a nls? > > > The kind of output that I get is: > > > Formula: y ~ exp.f(x, a, b) > > Parameters: > Estimate Std. Error t value Pr(>|t|) > a 1.381e+02 1.192e+01 11.583 3.19e-08 *** > b 1.790e-02 2.459e-03 7.279 6.19e-06 *** > --- > Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 > > Residual standard error: 13.21 on 13 degrees of freedom > > Number of iterations to convergence: 6 > Achieved convergence tolerance: 9.123e-06 > > > I know that my parameters are significant but I need to say something about > the whole model. > > Many thanks, > Nerak > > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/nls-how-do-you-know-if-the-model-is-significant-tp4632401.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.
