Hi, all.
I’m encountering a very odd, perplexing issue.
I have a TFile with a flat ntuple TTree. I’m defining a set of RooRealVar, putting these RooRealVar into a RooArgSet, and then using them to make a RooDataSet from the TTree I grab from the TFile.
But I’m noticing that I get many fewer entries if I include more if the RooRealVars into the RooArgSet, even if I’m not using the variables to reduce the dataset.
Here’s an example of what I’m doing:
[code]TTree* tree = (TTree*)infile->Get(“tofit”);
RooRealVar a(“a”, “a”, -1., 1.);
RooRealVar b(“b”, “b”, -1., 1.);
RooRealVar c(“c”, “c”, -1., 1.);
RooArgSet fitVars();
fitVars.add(a);
fitVars.add(b);
fitVars.add©;
RooDataSet dSet(“dSet”, “dSet”, tree, fitVars);
[/code]
Now, if I, for example, comment out the second two “fitVars.add” lines, I get an entirely different number of entries in my RooDataSet!
Is there a reason why this is happening? I seem to be losing statistics, and I can’t figure out why simply adding more variables to the RooArgSet would change what entries I grab from the tree.
I should also mention that if I simply plot the variables from the TTree to a TH1D, I see even more entries.