Normalization for projection of 2D RooSimultaneous with cut

[giaccaria]

Hi all,

I can happily plot fit result for my 2D simultaneous pdf, by doing:

combinedData.plotOn(frame, 
            ROOT.RooFit.CutRange("sigRegion"),
            ROOT.RooFit.Cut("channelCat==channelCat::%s" % chName) 
            ) 

combinedPdf.plotOn(frame, 
            ROOT.RooFit.Slice(channelCat, chName),
            ROOT.RooFit.ProjWData(ROOT.RooArgSet(channelCat), combinedData),
            ROOT.RooFit.Components(aComponent), 
            ROOT.RooFit.FillColor(aColor),
            ROOT.RooFit.DrawOption("F"))

Now, I want to plot the same results but with a cut on one of the 2 variables of these 2D plane,
so I tried to modify the combinedPdf.plotOn() part by adding:

            ROOT.RooFit.ProjectionRange("sigRegion")

where y.setRange("sigRegion", 0.9, 1)
but the Pdf seems to be not correctly normalized (too small number of events in it).

So googling around I find that I should actually use:

            ROOT.RooFit.ProjectionRange("sigRegion"),
            ROOT.RooFit.NormRange("sigRegion")

but this gives the warning:

[#0] WARNING:Plotting -- RooHist::getFitRangeNEvt() WARNING: Number of normalization events associated to histogram is not equal to number of events in histogram
                           due cut made in RooAbsData::plotOn() call. Automatic normalization over sub-range of plot variable assumes
                           that the effect of that cut is uniform across the plot, which may be an incorrect assumption. To be sure of
                           correct normalization explicit pass normalization information to RooAbsPdf::plotOn() call using Normalization()

so eventually tried:

            ROOT.RooFit.ProjectionRange("sigRegion"),
            ROOT.RooFit.NormRange("sigRegion"),
            ROOT.RooFit.Normalization(1.0, ROOT.RooAbsReal.RelativeExpected)

which still gives the same results as without this last line (trying 1 just to see what happens).

What’s the correct way of normalizating the projection + cut ?

---

ROOT Version: 6.08/06
Platform: Scientific Linux release 6.9
Compiler: Not Provided

---

[couet]

The title of your post mention TRatioPlot, but, reading it, it seems more related to RootFit .
I guess @moneta can help you.

[moneta]

This is a difficult and tricky question and I am sorry but I don’t know the answer. You will have to ask directly to the RooFit author.

Lorenzo

[giaccaria]

Thanks @couet and @moneta , I’ve changed the title to something more appropriate.

I hope @Wouter_Verkerke can help then.