[R] nls: how do you know if the model is significant?
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$fstatistic p.value-1-pf(f.stat[value],f.stat[numdf],f.stat[dendf]) Is there something similar for a nls? The kind of output that I get is: Formula: y ~ exp.f(x, a, b) Parameters: Estimate Std. Error t value Pr(|t|) a 1.381e+02 1.192e+01 11.583 3.19e-08 *** b 1.790e-02 2.459e-03 7.279 6.19e-06 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 13.21 on 13 degrees of freedom Number of iterations to convergence: 6 Achieved convergence tolerance: 9.123e-06 I know that my parameters are significant but I need to say something about the whole model. Many thanks, Nerak -- View this message in context: http://r.789695.n4.nabble.com/nls-how-do-you-know-if-the-model-is-significant-tp4632401.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] nls: how do you know if the model is significant?
I suggest you consult a local statistician. You could also post to a statistical help list like stats.stackexchange.com. Your query has nothing to do with R, but is rather about the meaningfulness (or lack thereof) of statistical significance in nonlinear modeling. -- Bert On Tue, Jun 5, 2012 at 6:49 AM, Nerak nera...@hotmail.com wrote: Hi all, I'm struggling with nls. How do you know if your model is significant? For a lm, you get a p-value, but you don't get it for a nls. Is there a way to calculate it? For a lm I use this: a-summary(lm(model ~obs)) f.stat-a$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.
Re: [R] nls: how do you know if the model is significant?
Here goes bert again with etiquette lessons. Why are you so crabby? On Jun 5, 11:16 am, Bert Gunter gunter.ber...@gene.com wrote: 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-sig... Sent from the R help mailing list archive at Nabble.com. __ r-h...@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guidehttp://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/pd... __ r-h...@r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.- Hide quoted text - - Show quoted text - __ 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.
