# fit nonlinear regression model to data

I was wondering how can I best fit nonlinear regression model to this data, using an R package.

How can I check if model is good fitted since $$R^2$$ value is not returned in most functions for nonlinear models?

(source: tarchomin.pl)

• What makes you think this data fits a nonlinear function and what function do you think that is? To me it looks pretty much like a horizontal line with a couple of outliers are 0. – John Jun 4 '14 at 15:02
• @John: Might as well partially fit an under-damped harmonic oscillation (hyperphysics.phy-astr.gsu.edu/hbase/oscda.html) or similar function. – Aleksandr Blekh Oct 26 '14 at 2:59