[R] non-linear fit and statistical significance

[Juan Munoz-Garcia]

Dear R users,

I’m using the constrOptim.nl<http://constrOptim.nl> to carry out non-linear fit with constraints between experimental and modelled data. As far as I understand the parameter “fval" indicates the goodness of this fit.
My first question is: Is the fval parameter similar to commonly used chi^2 parameter?
Second: if you’d need to decide which set of models best fit your experimental data by comparing the different fval values obtained, how can you use R to determine if the differences between fval values is statistically significant?

I´d appreciate your feedback.
Regards.
Juan C. Munoz-García

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