in my analysis I’m filling several histograms, in order to perform several operations later (scaling, dividing, filling THStak…). In order to properly handle the statistical errors (during this later operation), I wonder if before the histogram filling I should call a specific method (for the error)?
Search for “Sumw2” and “kIsAverage” in the TH1 class description.
I still wonder if I can apply these method after I’ve filled the histogram (or am I obliged to call them before I fill the histogram)? So for example, if I fill my 2 histograms (without Sumw2()):
then I call Sumw2();
then I divide:
Are the errors still handle properly?
I think it really only makes sense to call Sumw2 before filling (but others may disagree, of course).
ok, thank you for your help.