Hello DSPGuy and altenbach,
thanks again for your replay. So I will use the solution as given earlier (using this "Goodness of Fit.vi") as this shows good agreement to the NIST results AND (and this for sure has to be fixed) the documentation on the "residue" <-> "Restbetrag" from the "Nonlinear Curve Fit.VI" are inconsitend.
So in case that nothing will be changed to the "Nonlinear Curve Fit.VI" in future at least the example given from DSPGuy earlier should be given in the help of the "Nonlinear Curve Fit.VI" and the explanation that weight=(1/std. dev.)^2. This would have saved me lots of time.
Greetings Wolfgang
