RooHistError Class Reference

RooHistError is a singleton class used to calculate the error bars for each bin of a RooHist object.

Errors are calculated by integrating a specified area of a Poisson or Binomail error distribution.

Definition at line 25 of file RooHistError.h.

Classes
class	BinomialSumAsym
class	BinomialSumEff
class	PoissonSum

Public Member Functions
virtual	~RooHistError ()
Bool_t	getPoissonInterval (Int_t n, Double_t &mu1, Double_t &mu2, Double_t nSigma=1) const
	Return a confidence interval for the expected number of events given n observed (unweighted) events. More...
Bool_t	getBinomialIntervalAsym (Int_t n, Int_t m, Double_t &a1, Double_t &a2, Double_t nSigma=1) const
	Return 'nSigma' binomial confidence interval for (n,m). More...
Bool_t	getBinomialIntervalEff (Int_t n, Int_t m, Double_t &a1, Double_t &a2, Double_t nSigma=1) const
	Return 'nSigma' binomial confidence interval for (n,m). More...
Bool_t	getInterval (const RooAbsFunc *Qu, const RooAbsFunc *Ql, Double_t pointEstimate, Double_t stepSize, Double_t &lo, Double_t &hi, Double_t nSigma) const
	Calculate a confidence interval using the cumulative functions provided. More...

Static Public Member Functions
static const RooHistError &	instance ()
	Return a reference to a singleton object that is created the first time this method is called. More...
static RooAbsFunc *	createPoissonSum (Int_t n)
	Create and return a PoissonSum function binding. More...
static RooAbsFunc *	createBinomialSum (Int_t n, Int_t m, Bool_t eff)
	Create and return a BinomialSum function binding. More...

Private Member Functions
Bool_t	getPoissonIntervalCalc (Int_t n, Double_t &mu1, Double_t &mu2, Double_t nSigma=1) const
	Calculate a confidence interval for the expected number of events given n observed (unweighted) events. More...
	RooHistError ()
	Construct our singleton object. More...
Double_t	seek (const RooAbsFunc &f, Double_t startAt, Double_t step, Double_t value) const
	Scan f(x)-value until it changes sign. More...

Private Attributes
Double_t	_poissonLoLUT [1000]
Double_t	_poissonHiLUT [1000]

#include <RooHistError.h>

Constructor & Destructor Documentation

virtual RooHistError::~RooHistError ( )

inlinevirtual

Definition at line 28 of file RooHistError.h.

RooHistError::RooHistError ( )

private

Construct our singleton object.

Definition at line 59 of file RooHistError.cxx.

Member Function Documentation

RooAbsFunc * RooHistError::createBinomialSum ( Int_t  n, Int_t  m, Bool_t  eff  )

static

Create and return a BinomialSum function binding.

Definition at line 343 of file RooHistError.cxx.

RooAbsFunc * RooHistError::createPoissonSum ( Int_t  n )

static

Create and return a PoissonSum function binding.

Definition at line 334 of file RooHistError.cxx.

Bool_t RooHistError::getBinomialIntervalAsym	(	Int_t	n,
		Int_t	m,
		Double_t &	asym1,
		Double_t &	asym2,
		Double_t	nSigma = 1
	)		const

Return 'nSigma' binomial confidence interval for (n,m).

The result is return in asym1 and asym2. If the return values is kFALSE and error occurred.

Definition at line 133 of file RooHistError.cxx.

Bool_t RooHistError::getBinomialIntervalEff	(	Int_t	n,
		Int_t	m,
		Double_t &	asym1,
		Double_t &	asym2,
		Double_t	nSigma = 1
	)		const

Return 'nSigma' binomial confidence interval for (n,m).

The result is return in asym1 and asym2. If the return values is kFALSE and error occurred.

Definition at line 196 of file RooHistError.cxx.

Bool_t RooHistError::getInterval	(	const RooAbsFunc *	Qu,
		const RooAbsFunc *	Ql,
		Double_t	pointEstimate,
		Double_t	stepSize,
		Double_t &	lo,
		Double_t &	hi,
		Double_t	nSigma
	)		const

Calculate a confidence interval using the cumulative functions provided.

The interval will be "central" when both cumulative functions are provided, unless this would exclude the pointEstimate, in which case a one-sided interval pinned at the point estimate is returned instead.

Definition at line 263 of file RooHistError.cxx.

Bool_t RooHistError::getPoissonInterval	(	Int_t	n,
		Double_t &	mu1,
		Double_t &	mu2,
		Double_t	nSigma = 1
	)		const

Return a confidence interval for the expected number of events given n observed (unweighted) events.

The interval will contain the same probability as nSigma of a Gaussian. Uses a central interval unless this does not enclose the point estimate n (ie, for small n) in which case the interval is adjusted to start at n. This method uses a lookup table to return precalculated results for n<1000

Definition at line 79 of file RooHistError.cxx.

Referenced by RooTreeDataStore::weightError(), RooVectorDataStore::weightError(), and RooDataHist::weightError().

Bool_t RooHistError::getPoissonIntervalCalc ( Int_t  n, Double_t &  mu1, Double_t &  mu2, Double_t  nSigma = 1  ) const

private

Calculate a confidence interval for the expected number of events given n observed (unweighted) events.

The interval will contain the same probability as nSigma of a Gaussian. Uses a central interval unless this does not enclose the point estimate n (ie, for small n) in which case the interval is adjusted to start at n.

Definition at line 102 of file RooHistError.cxx.

const RooHistError & RooHistError::instance ( )

static

Return a reference to a singleton object that is created the first time this method is called.

Only one object will be constructed per ROOT session.

Definition at line 49 of file RooHistError.cxx.

Referenced by RooHist::addAsymmetryBin(), RooHist::addBin(), RooHist::addEfficiencyBin(), RooTreeDataStore::weightError(), RooVectorDataStore::weightError(), and RooDataHist::weightError().

Double_t RooHistError::seek ( const RooAbsFunc &  f, Double_t  startAt, Double_t  step, Double_t  value  ) const

private

Scan f(x)-value until it changes sign.

Start at the specified point and take constant steps of the specified size. Give up after 1000 steps.

Definition at line 313 of file RooHistError.cxx.

Member Data Documentation

Double_t RooHistError::_poissonHiLUT[1000]

private

Definition at line 44 of file RooHistError.h.

Double_t RooHistError::_poissonLoLUT[1000]

private

Definition at line 43 of file RooHistError.h.

---

The documentation for this class was generated from the following files:

• roofit/roofitcore/inc/RooHistError.h
• roofit/roofitcore/src/RooHistError.cxx