Fitting with ROOT and ROOFIT


I have histogram with angular distribution. Then I try to fit this histogram by gauss and get the ChiSquare/nDOF = 1909/97
Then I fit same histogram with ROOFIT using RooGaussian and after all xframe->chiSquare() return 15.5.
Can anyone, please, explain the difference? Does xframe show chi already divided by nDOF?
Thank you in advance.

RooFit returns you the chi2 already normalized in the RooPlot::chiSquare().

See Wouter answer