com.itemanalysis.psychometrics.irt.estimation

Class ItemFitG2

java.lang.Object

com.itemanalysis.psychometrics.irt.estimation.AbstractItemFitStatistic

com.itemanalysis.psychometrics.irt.estimation.ItemFitG2

All Implemented Interfaces:

ItemFitStatistic

public class ItemFitG2
extends AbstractItemFitStatistic

Field Summary

Fields inherited from class com.itemanalysis.psychometrics.irt.estimation.AbstractItemFitStatistic

expectedValues, irm, minExpectedCellCount, numberOfBins, numberOfCategories, rowMargin, rowThetaSum, table, totalCount, validRow

Constructor Summary

Constructors

Constructor and Description
ItemFitG2(ItemResponseModel irm, Cut thetaCut, int minExpectedCellCount) This constructor is designed for the case where the number of table rows and the boundaries are specified in thetaCut.

Method Summary

Modifier and Type	Method and Description
void	compute()
double	getDegreesOfFreedom()
double	getPValue()
double	getThetaAt(int i)
double	getValue()
void	increment(double theta, int itemResponse) Increment fit statistic.
void	increment(double theta, int itemResponse, double frequency)
protected void	initializeExpectedFrequencies()
java.lang.String	toString()

Methods inherited from class com.itemanalysis.psychometrics.irt.estimation.AbstractItemFitStatistic

condenseTable, getFrequencyAt, getProportionAt, getTotalCount, initialize, printContingencyTable, printMirtFormatTable

Methods inherited from class java.lang.Object

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

Constructor Detail

ItemFitG2

public ItemFitG2(ItemResponseModel irm,
                 Cut thetaCut,
                 int minExpectedCellCount)

This constructor is designed for the case where the number of table rows and the boundaries are specified in thetaCut. Values will be assigned to each bin using the increment(theta, itemResponse) method.

Parameters:

irm - an item response model object.

thetaCut - an object that divides the range of these into bins.

minExpectedCellCount - minimum expected value allowed in a table row.

Method Detail

increment

public void increment(double theta,
                      int itemResponse)

Increment fit statistic. The item response is zero based. It should be an ordered integer: 0, 1, 2, 3, ...

Parameters:

theta - EAP estimate of examinee ability

itemResponse - an item response with values starting at 0. The value of teh response is also the array index for the fit statistic.

increment

public void increment(double theta,
                      int itemResponse,
                      double frequency)

initializeExpectedFrequencies

protected void initializeExpectedFrequencies()

compute

public void compute()

getThetaAt

public double getThetaAt(int i)

getValue

public double getValue()

getDegreesOfFreedom

public double getDegreesOfFreedom()

getPValue

public double getPValue()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object