void loglike()
{
  using namespace RooFit ;
  using namespace RooStats ;
  
  RooWorkspace* wspace = new RooWorkspace();

  wspace->factory("obs[13]");
  wspace->factory("Poisson::countingModel(obs[13], sum(s[3,0,10],b[10]))"); // counting model

  RooDataSet* data = new RooDataSet("exampleData", "exampleData", *wspace->var("obs"));
  data->add(*wspace->var("obs"));

  ModelConfig modelConfig(new RooWorkspace());
  modelConfig.SetWorkspace(*wspace);
  modelConfig.SetPdf(*wspace->pdf("countingModel"));
  modelConfig.SetParametersOfInterest(*wspace->var("s"));
  modelConfig.SetNuisanceParameters(*wspace->var("b"));

  double confidenceLevel = 0.6827;

  ProfileLikelihoodCalculator plc(*data, modelConfig);
  plc.SetConfidenceLevel(confidenceLevel);
  LikelihoodInterval* plInt = plc.GetInterval();

  TCanvas* canvas = new TCanvas("canvas");
  TPad *up = new TPad("up","",0,0.5,1,1);
  TPad *down = new TPad("down","",0,0,1,0.5);

  canvas->cd();
  up->Draw();
  down->Draw();

  up->cd();
  LikelihoodIntervalPlot plot(plInt);
  plot.Draw("");
  canvas->Update();

  RooPlot *rh = (RooPlot*) plot.GetPlottedObject();

  return;
}