void rs500b_PrepareWorkspace_Poisson_withSystematics( TString fileName = "WS_Poisson_withSystematics.root", int type = 1 )
{
// use a RooWorkspace to store the pdf models, prior informations, list of parameters,...
RooWorkspace myWS("myWS");
// Observable
myWS.factory("x[0,0,1]") ;
// Pdf in observable,
myWS.factory("Uniform::sigPdf(x)") ;
myWS.factory("Uniform::bkgPdf(x)") ;
myWS.factory("SUM::model(S[100,0,1500]*sigPdf,B[1000,0,3000]*bkgPdf)") ;
// Background only pdf
myWS.factory("ExtendPdf::modelBkg(bkgPdf,B)") ;
// Priors
myWS.factory("Gaussian::priorNuisance(B,1000,200)") ;
myWS.factory("Uniform::priorPOI(S)") ;
// Definition of observables and parameters of interest
myWS.defineSet("observables","x");
myWS.defineSet("POI","S");
myWS.defineSet("parameters","B") ;
// Generate data
RooAbsData* data = 0;
// binned data with fixed number of events
if (type ==0) data = myWS.pdf("model")->generateBinned(*myWS.set("observables"),myWS.var("S")->getVal(),Name("data"));
// binned data with Poisson fluctuations
if (type ==1) data = myWS.pdf("model")->generateBinned(*myWS.set("observables"),Extended(),Name("data"));
// Asimov data: binned data without any fluctuations (average case)
if (type == 2) data = myWS.pdf("model")->generateBinned(*myWS.set("observables"),Name("data"),ExpectedData());
myWS.import(*data) ;
myWS.writeToFile(fileName);
std::cout << "\nRooFit model initialized and stored in " << fileName << std::endl;
// control plot of the generated data
RooPlot* plot = myWS.var("x")->frame();
data->plotOn(plot);
plot->DrawClone();
}
