[R] Nonlinear regression question

Greg Snow Greg.Snow at imail.org
Thu Sep 15 19:12:28 CEST 2011

What null hypothesis are you trying to test?  There is a standard null for linear models that makes sense in a large number of cases, but what the null is for non-linear regression is not obvious (and the coefficient = 0 may not even be possibly, let alone interesting).  If you can state what your null hypothesis is then there are ways to get p-values, but easier is to just compute confidence intervals for the parameter of interest and see if the null value is in the interval.

Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Tatiana Donnay
> Sent: Thursday, September 15, 2011 6:41 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Nonlinear regression question
> Hello,
> If I understand good, I can't have p-value for the nls model.
> I have 2 vectors. And I'am doing
> model <- nls(crf ~a*(1-exp(-x/b)) + c, data= d,
>               start = list(a=1, b=3, c=0))
> and I want to know If my result is significat, if I can't have p-value,
> how can I know it?
> Thank you
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