edu.ucla.stat.SOCR.distributions
Class PoissonDistribution

java.lang.Object
  edu.ucla.stat.SOCR.core.SOCRValueSettable
      edu.ucla.stat.SOCR.core.Distribution
          edu.ucla.stat.SOCR.distributions.PoissonDistribution

All Implemented Interfaces:

IValueSettable, Pluginable, java.util.Observer

public class PoissonDistribution
extends Distribution

A Java implementation of the Poisson distribution with specified Shift and Mean parameters http://en.wikipedia.org/wiki/Poisson_distribution.

Field Summary

Fields inherited from class edu.ucla.stat.SOCR.core.Distribution

applet, CONTINUOUS, DISCRETE, MAXMGFXVAL, MAXMGFYVAL, MINMGFXVAL, MIXED, name

Constructor Summary

PoissonDistribution()
Default constructor: creates a Poisson distribution with shift and lambda parameters equal to 0 & 1

PoissonDistribution(double l)

PoissonDistribution(double[] distData)

PoissonDistribution(float[] distData)

PoissonDistribution(int s, double l)

Method Summary

double	getCDF(double x) Compute the cumulative distribution function.
double	getDensity(double x) Define the Poisson getDensity function
double	getLambda() Get the lambda paramter
int	getLocation() Get the Location-Shift paramter
double	getMaxDensity() Compute the maximum getDensity
double	getMean() Compute the mean in closed form
double	getMGF(double t) Computes the moment generating function in closed form for a parameter t which lies in the domain of the distribution.
double	getMode() Compute the Mode in closed form
java.lang.String	getOnlineDescription() This method returns an online description of this distribution.
double	getPGF(double t) Computes the probability generating function in closed form for a parameter t which lies in the domain of the distribution.
double	getSD() Compute the variance in closed form
int	getShift()
double	getVariance() Compute the variance in closed form
void	initialize() used for some subclass to initialize before being used
double	inverseCDF(double probability) Inverse of the cumulative Poisson distribution function.
double	minimum(double[] distData) The method finds the minimum of a double array directly copied from ExponentialDistribution.java.
void	paramEstimate(double[] distData) Parameter estimation function from raw data For some reason this always OVERESTIMATES the SHIFT parameter.
void	setLambda(double r) Sets the lambda
void	setLocation(int s) Sets the Location parameter
void	setParameter(double l) Set the LAMBDA parameter
void	setParameters(int s, double l) Set the shift & lambda parameters
void	setShift(int s)
double	simulate() Simulate a value
void	valueChanged()

Methods inherited from class edu.ucla.stat.SOCR.core.Distribution

addObserver, betaCDF, comb, factorial, findGFRoot, findRoot, gamma, gammaCDF, getDisplayPane, getDomain, getFailureRate, getGFDerivative, getGFSecondDerivative, getInstance, getLocalHelp, getMean, getMedian, getMgfDomain, getName, getPGFDomain, getQuantile, getSampleMoment, getSOCRDistributionFunctors, getSOCRDistributions, getType, getVariance, logGamma, perm, sampleMean, sampleVar, setApplet, setDomain, setDomain, setMGFDomain, setMGFDomain, setMGFParameters, setMGFParameters, setMGFParameters, setMGFParameters, setParameters, setPGFDomain, setPGFDomain, setPGFParameters, setPGFParameters, setPGFParameters, setPGFParameters, update, valueChanged

Methods inherited from class edu.ucla.stat.SOCR.core.SOCRValueSettable

createComponentSetter, createValueSetter, createValueSetter, createValueSetter, createValueSetter, getComponentSetter, getComponentSetters, getValueSetter, getValueSetters

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PoissonDistribution

public PoissonDistribution()

Default constructor: creates a Poisson distribution with shift and lambda parameters equal to 0 & 1

PoissonDistribution

public PoissonDistribution(int s,
                           double l)

PoissonDistribution

public PoissonDistribution(double l)

PoissonDistribution

public PoissonDistribution(double[] distData)

PoissonDistribution

public PoissonDistribution(float[] distData)

Method Detail

initialize

public void initialize()

Description copied from class: Distribution

used for some subclass to initialize before being used

Overrides:

initialize in class Distribution

valueChanged

public void valueChanged()

Overrides:

valueChanged in class Distribution

setParameter

public void setParameter(double l)

Set the LAMBDA parameter

setParameters

public void setParameters(int s,
                          double l)

Set the shift & lambda parameters

setLocation

public void setLocation(int s)

Sets the Location parameter

setLambda

public void setLambda(double r)

Sets the lambda

getLocation

public int getLocation()

Get the Location-Shift paramter

getLambda

public double getLambda()

Get the lambda paramter

getShift

public int getShift()

getDensity

public double getDensity(double x)

Define the Poisson getDensity function

Specified by:

getDensity in class Distribution

getMaxDensity

public double getMaxDensity()

Compute the maximum getDensity

Overrides:

getMaxDensity in class Distribution

getMean

public double getMean()

Compute the mean in closed form

Overrides:

getMean in class Distribution

getMode

public double getMode()

Compute the Mode in closed form

paramEstimate

public void paramEstimate(double[] distData)

Parameter estimation function from raw data For some reason this always OVERESTIMATES the SHIFT parameter. We need a better analytical strategy for estimation of parameters here!

Overrides:

paramEstimate in class Distribution

setShift

public void setShift(int s)

minimum

public double minimum(double[] distData)

The method finds the minimum of a double array directly copied from ExponentialDistribution.java. annie che 20060714

getVariance

public double getVariance()

Compute the variance in closed form

Overrides:

getVariance in class Distribution

getSD

public double getSD()

Compute the variance in closed form

Overrides:

getSD in class Distribution

getCDF

public double getCDF(double x)

Compute the cumulative distribution function.

Overrides:

getCDF in class Distribution

getMGF

public double getMGF(double t)

Computes the moment generating function in closed form for a parameter t which lies in the domain of the distribution.

Overrides:

getMGF in class Distribution

getPGF

public double getPGF(double t)

Computes the probability generating function in closed form for a parameter t which lies in the domain of the distribution.

Overrides:

getPGF in class Distribution

inverseCDF

public double inverseCDF(double probability)

Inverse of the cumulative Poisson distribution function.

Overrides:

inverseCDF in class Distribution

Parameters:

probability - - a probability value in [0, 1]

Returns:

the value X for which P(x<X).

simulate

public double simulate()

Simulate a value

Overrides:

simulate in class Distribution

getOnlineDescription

public java.lang.String getOnlineDescription()

This method returns an online description of this distribution.

Overrides:

getOnlineDescription in class Distribution