Represents a yield and uncertainty obtained by counting weighted events. More...

#include <gamma_params.hpp>

Public Member Functions
	GammaParams ()
	Standard constructor initializing to unweighted count = 0, weight = 0. More...

	GammaParams (double n_effective, double weight)
	Constructs GammaParams with given number of unweighted events and weight. More...

	GammaParams (const GammaParams &)=default

GammaParams &	operator= (const GammaParams &)=default

	GammaParams (GammaParams &&)=default

GammaParams &	operator= (GammaParams &&)=default

	~GammaParams ()=default

void	SetNEffectiveAndWeight (double n_effective, double weight)
	Sets GammaParams by unweighted event count and weight. More...

void	SetYieldAndUncertainty (double yield, double uncertainty)
	Sets GammaParams by yield and uncertainty. More...

double	Yield () const
	Get the yield/rate. More...

void	Yield (double yield)
	Set the yield/rate. More...

double	Uncertainty () const
	Get the "sqrt(N)"-like uncertainty on the yield/rate. More...

void	Uncertainty (double uncertainty)
	Set the "sqrt(N)"-like uncertainty on the yield/rate. More...

double	NEffective () const
	Get the effective number of unweighted events. More...

void	NEffective (double n_effective)
	Set the effective number of unweighted events. More...

double	Weight () const
	Get the effective weight for the sample. More...

void	Weight (double weight)
	Set the effective weight for the sample. More...

double	CorrectedUncertainty () const
	Get the "sqrt(N+1)"-like uncertainty on the yield/rate. More...

GammaParams &	operator+= (const GammaParams &gp)
	Adds another GammaParams to *this. More...

GammaParams &	operator*= (double scale)
	Scale/multiply *this by a constant. More...

Private Attributes
double	n_effective_

double	weight_

Detailed Description

Represents a yield and uncertainty obtained by counting weighted events.

GammaParams uses two different representations of rate: one using the rate/yield and uncertainty and another using the number of unweighted events and the weight. In the case that all events have the same weight, the conversion is:

Yield or rate = (unweighted events) * (weight)
Uncertainty = sqrt(unweighted events) * weight
Unweighted events = (yield / uncertainty)^2
Weight = uncertainty^2/yield

In the case of events having different weights, GammaParams uses an approximation to get an effective number of unweighted events and an effective weight for the combination in the same way as ROOT's Sumw2;

The GammaParams::Uncertainty() method returns the "sqrt(N)"-like uncertainty on a Poisson mean correspdoning to a prior of Gamma(alpha=0, beta=0). This is the uncertainty used by the uncertainty getter and setter methods. The GammaParams::CorrectedUncertainty() returns the "sqrt(N+1)"-like uncertainty corresponding to a prior of Gamma(alpha=1, beta=0).

Definition at line 6 of file gamma_params.hpp.

Constructor & Destructor Documentation

GammaParams::GammaParams ( )

Standard constructor initializing to unweighted count = 0, weight = 0.

Definition at line 35 of file gamma_params.cpp.

GammaParams::GammaParams	(	double	n_effective,
		double	weight
	)

Constructs GammaParams with given number of unweighted events and weight.

Parameters

[in]	n_effective	Effective number of unweighted events
[in]	weight	Effective weight of sample

Definition at line 47 of file gamma_params.cpp.

GammaParams::GammaParams ( const GammaParams & )

default

GammaParams::GammaParams ( GammaParams && )

default

GammaParams::~GammaParams ( )

default

Member Function Documentation

double GammaParams::CorrectedUncertainty ( ) const

Get the "sqrt(N+1)"-like uncertainty on the yield/rate.

Returns: The "sqrt(N+1)"-like uncertainty corresponding to a prior of Gamma(alpha=1, beta=0) on the Poisson rate. This is not the uncertainty used by the GammaParams setter methods.

Definition at line 161 of file gamma_params.cpp.

References n_effective_, and weight_.

Referenced by operator<<().

double GammaParams::NEffective ( ) const

Get the effective number of unweighted events.

Returns: Effective number of unweighted events

Definition at line 127 of file gamma_params.cpp.

References n_effective_.

Referenced by operator*=(), operator+=(), operator<<(), and Weight().

void GammaParams::NEffective ( double n_effective )

Set the effective number of unweighted events.

Parameters

[in] n_effective Effective number of unweighted events

Definition at line 135 of file gamma_params.cpp.

References SetNEffectiveAndWeight(), and Weight().

GammaParams & GammaParams::operator*= ( double scale )

Scale/multiply *this by a constant.

The yield and uncertainty scale linearly.

Parameters

[in] scale Amount by which to scale *this

Returns: Reference to *this

Definition at line 193 of file gamma_params.cpp.

References NEffective(), SetNEffectiveAndWeight(), and Weight().

GammaParams & GammaParams::operator+= ( const GammaParams & gp )

Adds another GammaParams to *this.

Uses a Sumw2-like approximation to obtain effective number of unweighted events and weight. The resulting yield is the sum of the original two yields. The resulting uncertainty is the square-root-of-the-sum-of-squares of the original uncertainties.

Parameters

[in] gp GammaParams to add to *this

Returns: Reference to *this

Definition at line 176 of file gamma_params.cpp.

References NEffective(), SetNEffectiveAndWeight(), SetYieldAndUncertainty(), Uncertainty(), Weight(), and Yield().

GammaParams& GammaParams::operator= ( const GammaParams & )

default

GammaParams& GammaParams::operator= ( GammaParams && )

default

void GammaParams::SetNEffectiveAndWeight	(	double	n_effective,
		double	weight
	)

Sets GammaParams by unweighted event count and weight.

Resets the yield/rate and uncertainty to corresponding values.

Parameters

[in]	n_effective	The effective number of _unweighted_events. It need not be an integer.
[in]	weight	The effective weight of the sample

Definition at line 82 of file gamma_params.cpp.

References n_effective_, and weight_.

Referenced by NEffective(), operator*=(), operator+=(), and Weight().

void GammaParams::SetYieldAndUncertainty	(	double	yield,
		double	uncertainty
	)

Sets GammaParams by yield and uncertainty.

Resets the number of unweighted events and effective weight to corresponding values.

Parameters

[in]	yield	The weighted number of events
[in]	uncertainty	The "sqrt(N)"-like uncertainty on the yield/rate.

See also: GammaParams::Uncertainty()

Definition at line 63 of file gamma_params.cpp.

References n_effective_, and weight_.

Referenced by operator+=(), Uncertainty(), and Yield().

double GammaParams::Uncertainty ( ) const

Get the "sqrt(N)"-like uncertainty on the yield/rate.

Returns: The "sqrt(N)"-like uncertainty corresponding to a prior of Gamma(alpha=0, beta=0) on the Poisson rate. This is the uncertainty used by the GammaParams setter methods.

Definition at line 109 of file gamma_params.cpp.

References n_effective_, and weight_.

Referenced by operator+=(), and Yield().

void GammaParams::Uncertainty ( double uncertainty )

Set the "sqrt(N)"-like uncertainty on the yield/rate.

Parameters

[in] uncertainty The "sqrt(N)"-like uncertainty corresponding to a prior of Gamma(alpha=0, beta=0) on the Poisson rate. This is the uncertainty used by GammaParams::Uncertainty().

Definition at line 119 of file gamma_params.cpp.

References SetYieldAndUncertainty(), and Yield().

double GammaParams::Weight ( ) const

Get the effective weight for the sample.