com.itemanalysis.psychometrics.reliability

Class CoefficientAlpha

java.lang.Object

com.itemanalysis.psychometrics.reliability.AbstractScoreReliability

com.itemanalysis.psychometrics.reliability.CoefficientAlpha

All Implemented Interfaces:

ScoreReliability, java.lang.Comparable<ScoreReliability>

public class CoefficientAlpha
extends AbstractScoreReliability

Computes Coefficient alpha (aka Cronbach's alpha).

Author:

J. Patrick Meyer

Field Summary

Fields inherited from class com.itemanalysis.psychometrics.reliability.AbstractScoreReliability

matrix, nItems

Constructor Summary

Constructors

Constructor and Description
CoefficientAlpha(CovarianceMatrix matrix) Constructor for coefficient alpha.
CoefficientAlpha(double[][] matrix)

Method Summary

Modifier and Type	Method and Description
ScoreReliabilityType	getType() Type of reliability estimate
double[]	itemDeletedReliability() Computes reliability with each item omitted in turn.
java.lang.String	printItemDeletedSummary(java.util.ArrayList<VariableAttributes> var) A String representation of all item deleted reliability estimates.
java.lang.String	toString()
double	value() Compute the value of coefficient alpha.

Methods inherited from class com.itemanalysis.psychometrics.reliability.AbstractScoreReliability

compareTo, confidenceInterval, confidenceIntervalToString, equals, hashCode, totalVariance

Methods inherited from class java.lang.Object

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

Constructor Detail

CoefficientAlpha

public CoefficientAlpha(CovarianceMatrix matrix)

Constructor for coefficient alpha.

Parameters:

matrix - an inter-item correlation matrix

CoefficientAlpha

public CoefficientAlpha(double[][] matrix)

Method Detail

value

public double value()

Compute the value of coefficient alpha.

Returns:

reliability estimate

itemDeletedReliability

public double[] itemDeletedReliability()

Computes reliability with each item omitted in turn. The first element in the array is the reliability estimate without the first item. The second item in the array is the reliability estimate without the second item and so on.

Returns:

array of item deleted estimates.

getType

public ScoreReliabilityType getType()

Description copied from interface: ScoreReliability

Type of reliability estimate

Returns:

type of reliability estimate.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

printItemDeletedSummary

public java.lang.String printItemDeletedSummary(java.util.ArrayList<VariableAttributes> var)

Description copied from interface: ScoreReliability

A String representation of all item deleted reliability estimates.

Parameters:

var - VariableAttributes that provide the variable names.

Returns: