rs801_HypoTestInverterOriginal.C

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/// \file
/// \ingroup tutorial_roostats
/// \notebook -js
/// An example of using the HypoTestInverterOriginal class
///
/// \macro_image
/// \macro_output
/// \macro_code
///
/// \author Gregory Schott

#include "RooRealVar.h"
#include "RooConstVar.h"
#include "RooProdPdf.h"
#include "RooWorkspace.h"
#include "RooDataSet.h"
#include "RooPolynomial.h"
#include "RooAddPdf.h"
#include "RooExtendPdf.h"

#include "RooStats/HypoTestInverterOriginal.h"
#include "RooStats/HypoTestInverterResult.h"
#include "RooStats/HypoTestInverterPlot.h"
#include "RooStats/HybridCalculatorOriginal.h"

#include "TGraphErrors.h"

using namespace RooFit;
using namespace RooStats;

void rs801_HypoTestInverterOriginal()
{
   // prepare the model
   RooRealVar lumi("lumi", "luminosity", 1);
   RooRealVar r("r", "cross-section ratio", 3.74, 0, 50);
   RooFormulaVar ns("ns", "1*r*lumi", RooArgList(lumi, r));
   RooRealVar nb("nb", "background yield", 1);
   RooRealVar x("x", "dummy observable", 0, 1);
   RooConstVar p0(RooFit::RooConst(0));
   RooPolynomial flatPdf("flatPdf", "flat PDF", x, p0);
   RooAddPdf totPdf("totPdf", "S+B model", RooArgList(flatPdf, flatPdf), RooArgList(ns, nb));
   RooExtendPdf bkgPdf("bkgPdf", "B-only model", flatPdf, nb);
   RooDataSet *data = totPdf.generate(x, 1);

   // prepare the calculator
   HybridCalculatorOriginal myhc(*data, totPdf, bkgPdf, 0, 0);
   myhc.SetTestStatistic(2);
   myhc.SetNumberOfToys(1000);
   myhc.UseNuisance(false);

   // run the hypothesis-test inversion
   HypoTestInverterOriginal myInverter(myhc, r);
   myInverter.SetTestSize(0.10);
   myInverter.UseCLs(true);
   // myInverter.RunFixedScan(5,1,6);
   // scan for a 95% UL
   myInverter.RunAutoScan(3., 5, myInverter.Size() / 2, 0.005);
   // run an alternative autoscan algorithm
   // myInverter.RunAutoScan(1,6,myInverter.Size()/2,0.005,1);
   // myInverter.RunOnePoint(3.9);

   HypoTestInverterResult *results = myInverter.GetInterval();

   HypoTestInverterPlot myInverterPlot("myInverterPlot", "", results);
   TGraphErrors *gr1 = myInverterPlot.MakePlot();
   gr1->Draw("ALP");

   double ulError = results->UpperLimitEstimatedError();

   double upperLimit = results->UpperLimit();
   std::cout << "The computed upper limit is: " << upperLimit << std::endl;
   std::cout << "an estimated error on this upper limit is: " << ulError << std::endl;
   // expected result: 4.10
}
int main()
{
   rs801_HypoTestInverterOriginal();
}