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Reference Guide
Zbi_Zgamma.C
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1 /// \file
2 /// \ingroup tutorial_roostats
3 /// \notebook -js
4 /// Demonstrate Z_Bi = Z_Gamma
5 ///
6 /// \macro_image
7 /// \macro_output
8 /// \macro_code
9 ///
10 /// \author Kyle Cranmer & Wouter Verkerke
11 
12 #include "RooRealVar.h"
13 #include "RooProdPdf.h"
14 #include "RooWorkspace.h"
15 #include "RooDataSet.h"
16 #include "TCanvas.h"
17 #include "TH1.h"
18 
19 using namespace RooFit;
20 using namespace RooStats;
21 
22 void Zbi_Zgamma()
23 {
24 
25  // Make model for prototype on/off problem
26  // Pois(x | s+b) * Pois(y | tau b )
27  // for Z_Gamma, use uniform prior on b.
28  RooWorkspace *w1 = new RooWorkspace("w", true);
29  w1->factory("Poisson::px(x[150,0,500],sum::splusb(s[0,0,100],b[100,0,300]))");
30  w1->factory("Poisson::py(y[100,0,500],prod::taub(tau[1.],b))");
31  w1->factory("Uniform::prior_b(b)");
32 
33  // construct the Bayesian-averaged model (eg. a projection pdf)
34  // p'(x|s) = \int db p(x|s+b) * [ p(y|b) * prior(b) ]
35  w1->factory("PROJ::averagedModel(PROD::foo(px|b,py,prior_b),b)");
36 
37  // plot it, blue is averaged model, red is b known exactly
38  RooPlot *frame = w1->var("x")->frame();
39  w1->pdf("averagedModel")->plotOn(frame);
40  w1->pdf("px")->plotOn(frame, LineColor(kRed));
41  frame->Draw();
42 
43  // compare analytic calculation of Z_Bi
44  // with the numerical RooFit implementation of Z_Gamma
45  // for an example with x = 150, y = 100
46 
47  // numeric RooFit Z_Gamma
48  w1->var("y")->setVal(100);
49  w1->var("x")->setVal(150);
50  RooAbsReal *cdf = w1->pdf("averagedModel")->createCdf(*w1->var("x"));
51  cdf->getVal(); // get ugly print messages out of the way
52 
53  cout << "Hybrid p-value = " << cdf->getVal() << endl;
54  cout << "Z_Gamma Significance = " << PValueToSignificance(1 - cdf->getVal()) << endl;
55 
56  // analytic Z_Bi
57  double Z_Bi = NumberCountingUtils::BinomialWithTauObsZ(150, 100, 1);
58  std::cout << "Z_Bi significance estimation: " << Z_Bi << std::endl;
59 
60  // OUTPUT
61  // Hybrid p-value = 0.999058
62  // Z_Gamma Significance = 3.10804
63  // Z_Bi significance estimation: 3.10804
64 }
RooCmdArg LineColor(Color_t color)
Definition: Rtypes.h:64
Double_t PValueToSignificance(Double_t pvalue)
returns one-sided significance corresponding to a p-value
Definition: RooStatsUtils.h:50
virtual RooPlot * plotOn(RooPlot *frame, const RooCmdArg &arg1=RooCmdArg::none(), const RooCmdArg &arg2=RooCmdArg::none(), const RooCmdArg &arg3=RooCmdArg::none(), const RooCmdArg &arg4=RooCmdArg::none(), const RooCmdArg &arg5=RooCmdArg::none(), const RooCmdArg &arg6=RooCmdArg::none(), const RooCmdArg &arg7=RooCmdArg::none(), const RooCmdArg &arg8=RooCmdArg::none(), const RooCmdArg &arg9=RooCmdArg::none(), const RooCmdArg &arg10=RooCmdArg::none()) const
Helper calling plotOn(RooPlot*, RooLinkedList&) const.
Definition: RooAbsPdf.h:118
RooAbsReal * createCdf(const RooArgSet &iset, const RooArgSet &nset=RooArgSet())
Create a cumulative distribution function of this p.d.f in terms of the observables listed in iset...
Definition: RooAbsPdf.cxx:3370
The namespace RooFit contains mostly switches that change the behaviour of functions of PDFs (or othe...
Double_t BinomialWithTauObsZ(Double_t nObs, Double_t bExp, Double_t tau)
virtual void setVal(Double_t value)
Set value of variable to &#39;value&#39;.
Definition: RooRealVar.cxx:252
Double_t getVal(const RooArgSet *normalisationSet=nullptr) const
Evaluate object.
Definition: RooAbsReal.h:87
RooPlot * frame(const RooCmdArg &arg1, const RooCmdArg &arg2=RooCmdArg::none(), const RooCmdArg &arg3=RooCmdArg::none(), const RooCmdArg &arg4=RooCmdArg::none(), const RooCmdArg &arg5=RooCmdArg::none(), const RooCmdArg &arg6=RooCmdArg::none(), const RooCmdArg &arg7=RooCmdArg::none(), const RooCmdArg &arg8=RooCmdArg::none()) const
Create a new RooPlot on the heap with a drawing frame initialized for this object, but no plot contents.
A RooPlot is a plot frame and a container for graphics objects within that frame. ...
Definition: RooPlot.h:44
Namespace for the RooStats classes.
Definition: Asimov.h:20
RooAbsPdf * pdf(const char *name) const
Retrieve p.d.f (RooAbsPdf) with given name. A null pointer is returned if not found.
RooAbsReal is the common abstract base class for objects that represent a real value and implements f...
Definition: RooAbsReal.h:59
RooRealVar * var(const char *name) const
Retrieve real-valued variable (RooRealVar) with given name. A null pointer is returned if not found...
RooFactoryWSTool & factory()
Return instance to factory tool.
The RooWorkspace is a persistable container for RooFit projects.
Definition: RooWorkspace.h:43
virtual void Draw(Option_t *options=0)
Draw this plot and all of the elements it contains.
Definition: RooPlot.cxx:712