When I use some pdf to fit (unbinned likelihood fitting) a dataset which is weighted by positive and negative value like
RooAbsPdf somePdf; // some Pdf RooAbsData* wgtdata; // Dataset with positive and negative weight RooFitResult* fitres = somePdf.fitTo (*wgtdata, RooFit::Save(kTRUE), RooFit::SumW2Error(kTRUE)); std::cout << fitres->minNll() << std::endl;
I got a very strange value for
fitres->minNll() like 70.23 for example. If I came back to use unweight dataset associated with that weighted dataset, I got 230463 for example. Therefore, I want to ask
The later is correct?
Is this a bug for roofit when it handles weighted data?
How do I avoid this issue when I want to use minNll information?