I have been asked by a reviewer to give Goodness of fits to some curves in a manuscript but I am uncertain what is the most correct way to do it. The data is from non-linear regression of Michaelis-Menten data and I have already given the standard errors of the data in a separate table so it is rather the curve fitting that needs to be included. In GraphPad Prism there are four different parameters that I get:
R squared
Degrees of freedom
Sum of squares
Sy.x
As I have understood, it is not appropriate to only use R squared for nonlinear regression but is it okay to give it together with degrees of freedom? I am also wondering about if Sy.x is more appropriate to use (it is function related to the standard deviation of the residuals).
With this program you can fit the data in the Michaelis-Menten model and it will give you a good estimation of the reliability of the parameters:
www.lerenisplezant.be/fitting.htm
(On condition you enter realistic values for the precision of your measurements!)
If you can send your data I can show you.
Try using this great and free app to fit your data to several models
You Can also upload data as csv file
https://play.google.com/store/apps/details?id=com.curveregression
Thanks a lot for all the suggestions. In the end I decided to just use R2 values although I am aware that this is not ideal for nonlinear regression. Other alternatives (looking for residuals etc) were simply too extensive to use in this case with just a simple kinetic analysis.
Anders Hofer If you can send me some data I can show you what my program will say. It might be different from what you have, because of the improved least squares algorithm. I'll do it free of charge, because I am collection examples to prove the usefullnes of my software.
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