Weighted RooDataSet

Roofit and RooStats
1

Hi, I have 3 root files with TTrees that contain some observables and the event weight
In my fit program I want to merge the three samples in a unique RooDataSet and fit it with RooSimultaneous.

for(int i=0; i<3; i++){
h[i] = (TTree*)f[i]->Get( “merged” );
data[i] = new RooDataSet(“data”, “data”, *obs, Import(h[i]));
reducedData[i] = (RooDataSet) data[i]->reduce(cut.c_str());
reducedData[i]->SetName(“reducedData”);
// create weightfed data set
datawS[i] = new RooDataSet(reducedData[i]->GetName(), reducedData[i]->GetTitle(), reducedData[i], *reducedData[i]->get(), 0, “N_LsigR_sw”); //-----------> The weight is correctly assigned
datawS[i]->Print(“V”);
}

RooCategory selection(“selection”,“selection”);
selection.defineType(“prompt”);
selection.defineType(“fromB”);
selection.defineType(“MCB”);
RooDataSet *combData = new RooDataSet(“combData”, “combined data”, RooArgSet(D0IP), Index(selection), Import(“prompt”,*datawS[0]), Import(“fromB”,*datawS[1]),Import(“MCB”,*datawS[2]));

RooFormulaVar D0logIP(“D0logIP”, “log(D0 IP)”, “log(@0)”, RooArgList(D0IP)); // check units
RooRealVar D0logIPvar = (RooRealVar) combData->addColumn(D0logIP);

combData doesn’t seem to propagate the weight since I get this message:

DataStore reducedData (merged)
Observables:
1) D0_IP_OWNPV = 0.0277355 L(0 - 100000) // [mm] "D0 IP"
Dataset variable “N_LsigR_sw” is interpreted as the event weight

DataStore reducedData (merged)
Contains 116 entries
Observables:
1) D0_IP_OWNPV = 0.164524 L(0 - 100000) // [mm] "D0 IP"
Dataset variable “N_LsigR_sw” is interpreted as the event weight

DataStore reducedData (merged)
Contains 21162 entries
Observables:
1) D0_IP_OWNPV = 0.513287 L(0 - 100000) // [mm] "D0 IP"
Dataset variable “N_LsigR_sw” is interpreted as the event weight

29844
DataStore combData (merged)
Contains 29844 entries
Observables:
1) selection = prompt "selection"
2) D0_IP_OWNPV = 0.0277355 L(0 - 100000) // [mm] "D0 IP"
3) D0logIP = -3.58504 C L(-7 - 3) “log(D0 IP)”

How can I assign the weight also to combData?
Many thanks
Stefania

2

Hi Stefania,

You will need to repeat the WeightVar() argument in the constructor of the combined dataset.

Wouter

3

Hi Wouter,

I am having the same trouble, only, I am not allowed to add the WeightVar() argument to the constructor since maximum 11 arguments is allowed and for my simFit I need to pass 12 (WeightVar() included). Can you suggest some similar solution for my case ?

Thank you !
Best,
Jaroslav

4

I guess I have found a solution :

RooDataSet * combData=new RooDataSet("combData", "combined data", RooArgSet(B_VTX_mass,GLC_DDW_weight), Index(*sample), 
                                       Import("controlsignalRAD", *data_signalRAD_ctl),
                                       Import("controlsignalNONRAD", *data_signalNONRAD_ctl), 
                                       Import("controljpsipi", *data_jpsipi_ctl),WeightVar("GLC_DDW_weight"));
RooDataSet * combData1=new RooDataSet("combData1", "combined data1", RooArgSet(B_VTX_mass), Index(*sample), Import("physics", *data), 
                                       Import("controlbckgPRDStep", *PRDbigstep_data_ctl), 
                                       Import("controlbckgPRDBump", *PRDbump_data_ctl), 
                                       Import("controlbckgPRDEE", *PRDothers_data_ctl));
combData->append(*combData1);

Sorry for the noise, just let me know if it is obviously not correct, it works in the simfit without problems though.
Cheers,
Jaroslav

5

Thank you very much Jaroslav. Your solution was very useful to me.

Cheers,
Santiago