com.itemanalysis.psychometrics.measurement

Class ItemStats

java.lang.Object

com.itemanalysis.psychometrics.measurement.ItemStats

public class ItemStats
extends java.lang.Object

This class computes statistics for individual item response options. It is used by the ClassicalItem class in a classical item analysis.

Author:

J. Patrick Meyer

Constructor Summary

Constructors

Constructor and Description
ItemStats(java.lang.Object id, boolean biasCorrection, boolean pearson, boolean continuousItem)
ItemStats(java.lang.Object id, boolean biasCorrection, boolean pearson, boolean continuousItem, boolean dIndex)

Method Summary

Modifier and Type	Method and Description
double	getDifficulty()
double	getDIndex()
double	getDindexLower()
double	getDindexUpper()
double	getDiscrimination()
java.lang.Object	getId()
double	getStdDev()
void	increment(double testScore, double itemScore) Incrementally update the item statistics
void	incrementDindex(double itemScore, double testScore, double lowCut, double upperCut) The D index must be incremented in a second loop after test scores have been computed and percentiles computed.
java.lang.String	toString() A string that contains all of the item statistics.

Methods inherited from class java.lang.Object

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

Constructor Detail

ItemStats

public ItemStats(java.lang.Object id,
                 boolean biasCorrection,
                 boolean pearson,
                 boolean continuousItem)

ItemStats

public ItemStats(java.lang.Object id,
                 boolean biasCorrection,
                 boolean pearson,
                 boolean continuousItem,
                 boolean dIndex)

Method Detail

increment

public void increment(double testScore,
                      double itemScore)

Incrementally update the item statistics

Parameters:

testScore - sum score on teh total test

itemScore - score on teh individual item (or response option)

incrementDindex

public void incrementDindex(double itemScore,
                            double testScore,
                            double lowCut,
                            double upperCut)

The D index must be incremented in a second loop after test scores have been computed and percentiles computed. Use this method to increment the D index.

Parameters:

itemScore - item response score

testScore - test score

lowCut - test score cutoff value for lower group

upperCut - test score cutoff value for the upper group

getId

public java.lang.Object getId()

Returns:

id of the response option

getDifficulty

public double getDifficulty()

getStdDev

public double getStdDev()

getDiscrimination

public double getDiscrimination()

getDindexLower

public double getDindexLower()

getDindexUpper

public double getDindexUpper()

getDIndex

public double getDIndex()

toString

public java.lang.String toString()

A string that contains all of the item statistics.

Overrides:

toString in class java.lang.Object

Returns:

string of estimated statistics