Hello roofitters,
I’m using RooFit to fit a voigtian signal + exponential background to an unbinned data set.
There are 6 parameters: nsig, nbkg, exp, mean, width and sigma(gaussian resolution).
Is there a way to give RooFit only the initial guess without constraining the parameters, such that the fit will be efficient and will return a sane result ?
I tried removing the limits from the RooRealVar parameter definition, leaving just the initial guess, but then the fit simply gave me my initial guess with errors=0 for all 6 parameters.
The problem is that to get a good fit result with the most loose parameters-limits, I’, still feeling very biased since I happen to know the “correct” result.
btw, a simple chi2 (binned) fit to the same distribution, using ROOT, gives a perfect result, when supplied only with the initial guess without any limitations on the parameters and without defining any step sizes.
Best,
Noam