What should I believe in nonlinear curve fitting, Chi-square or R-square?

Nonlinear Least Squares

Curve fitting using PSO?

Nonlinear error function values must be less than linear models

Can anyone help with an algorithm to compute baseline in a

616 questions with answers in NONLINEAR

What type of statistical model should I use for dichotomous

Chi-squared calculation for (nonlinear) model goodness of fit for data with trials - Cross Validated

Curve Fitting

How to combine multiple probability distributions of measurements

Can you help me for image processing system in Matlab?

Why Is There No R-Squared for Nonlinear Regression?

Nonlinear Least Squares