com.itemanalysis.psychometrics.irt.estimation

Class ItemResponseVector

java.lang.Object

com.itemanalysis.psychometrics.irt.estimation.ItemResponseVector

All Implemented Interfaces:

java.lang.Comparable<ItemResponseVector>

public class ItemResponseVector
extends java.lang.Object
implements java.lang.Comparable<ItemResponseVector>

A class for storing the item response vector and frequency counts. This class is designed for storing summary information for marginal maximum likelihood estimation. It is also designed for use with IRT Person scoring. The item response vector should be ordered integers starting at 0. The code -1 indicates a missing response.

Field Summary

Fields

Modifier and Type	Field and Description
protected double	freq Number of times the response vector is observed in the sample.
protected int	nItems Number of items in the response vector
protected byte[]	response The item response vector.
protected double	sumScore Sum of the response vector, excluding missing responses.
protected double	validResponses Number of non-missing item responses.

Constructor Summary

Constructors

Constructor and Description
ItemResponseVector(byte[] response, double freq) A constructor that is designed for storing all response vectors during MML estimation.
ItemResponseVector(int nItems) A constructor that only requires the number of items.
ItemResponseVector(java.lang.String groupID, java.util.ArrayList<java.lang.Byte> response, java.util.ArrayList<VariableName> itemName, double freq)
ItemResponseVector(java.lang.String groupID, byte[] response, java.util.ArrayList<VariableName> itemName, double freq)
ItemResponseVector(java.lang.String groupID, byte[] response, double freq) A constructor that is designed for storing all response vectors during MML estimation.
ItemResponseVector(java.lang.String groupID, byte[] response, VariableName[] itemName, double freq)
ItemResponseVector(java.lang.String groupID, int nItems) A constructor that takes an argument for the group ID and number of items.

Method Summary

Modifier and Type	Method and Description
void	clearResponseVector() Resets the response vector and frequency counts to zero.
int	compareTo(ItemResponseVector other)
boolean	equals(java.lang.Object o)
double	getFrequency() Gets the frequency count for this response vector.
java.lang.String	getGroupID() Group indicator for use with multigroup estimation.
int	getNumberOfItems()
double	getPosteriorProbability()
byte	getResponseAt(int itemPosition) Get item response at given item position.
byte	getResponseAt(java.lang.String name)
byte	getResponseAt(VariableName variableName) Get item response by the variable name
double	getSumScore()
int	getValidResponseCount()
int	hashCode()
java.lang.String	printResponseVector()
void	setFrequency(double freq)
void	setPosteriorProbability(double posteriorProbability)
void	setResponseVector(byte[] response) Use this method to add an entire item response vector for a single examinee.
java.lang.String	toString() A string representation of the response string.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

response

protected byte[] response

The item response vector.

freq

protected double freq

Number of times the response vector is observed in the sample. It could also be a smapling weight.

validResponses

protected double validResponses

Number of non-missing item responses.

sumScore

protected double sumScore

Sum of the response vector, excluding missing responses.

nItems

protected int nItems

Number of items in the response vector

Constructor Detail

ItemResponseVector

public ItemResponseVector(java.lang.String groupID,
                          byte[] response,
                          VariableName[] itemName,
                          double freq)

ItemResponseVector

public ItemResponseVector(java.lang.String groupID,
                          byte[] response,
                          java.util.ArrayList<VariableName> itemName,
                          double freq)

ItemResponseVector

public ItemResponseVector(java.lang.String groupID,
                          java.util.ArrayList<java.lang.Byte> response,
                          java.util.ArrayList<VariableName> itemName,
                          double freq)

ItemResponseVector

public ItemResponseVector(java.lang.String groupID,
                          byte[] response,
                          double freq)

A constructor that is designed for storing all response vectors during MML estimation.

Parameters:

groupID - a group indicator code.

response - a response vector.

ItemResponseVector

public ItemResponseVector(byte[] response,
                          double freq)

A constructor that is designed for storing all response vectors during MML estimation.

Parameters:

response - a response vector.

ItemResponseVector

public ItemResponseVector(java.lang.String groupID,
                          int nItems)

A constructor that takes an argument for the group ID and number of items.

Parameters:

groupID - the group ID code.

nItems - the number of items in the response vector.

ItemResponseVector

public ItemResponseVector(int nItems)

A constructor that only requires the number of items.

Parameters:

nItems - the number of items in the response vector.

Method Detail

clearResponseVector

public void clearResponseVector()

Resets the response vector and frequency counts to zero.

setResponseVector

public void setResponseVector(byte[] response)

Use this method to add an entire item response vector for a single examinee. Also use it to change the response vector. This method is primarily designed for use with IRT person scoring in IrtExaminee.

Parameters:

response - item response

getGroupID

public java.lang.String getGroupID()

Group indicator for use with multigroup estimation.

Returns:

group indicator

getResponseAt

public byte getResponseAt(int itemPosition)

Get item response at given item position.

Parameters:

itemPosition - position of item in array

Returns:

item response

getResponseAt

public byte getResponseAt(VariableName variableName)

Get item response by the variable name

Parameters:

variableName - item for which the response is needed

Returns:

getResponseAt

public byte getResponseAt(java.lang.String name)

getFrequency

public double getFrequency()

Gets the frequency count for this response vector.

Returns:

frequency count.

setFrequency

public void setFrequency(double freq)

getSumScore

public double getSumScore()

getNumberOfItems

public int getNumberOfItems()

getValidResponseCount

public int getValidResponseCount()

setPosteriorProbability

public void setPosteriorProbability(double posteriorProbability)

getPosteriorProbability

public double getPosteriorProbability()

toString

public java.lang.String toString()

A string representation of the response string.

Overrides:

toString in class java.lang.Object

Returns:

response string.

printResponseVector

public java.lang.String printResponseVector()

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

compareTo

public int compareTo(ItemResponseVector other)

Specified by:

compareTo in interface java.lang.Comparable<ItemResponseVector>