Package edu.cmu.tetrad.search.utils

Class DeltaSextadTest

java.lang.Object

edu.cmu.tetrad.search.utils.DeltaSextadTest

public class DeltaSextadTest
extends Object

Implements a test for simultaneously zero sextads in the style of Bollen, K. (1990). Sociological Methods and Research 19, 80-92 and Bollen and Ting, Confirmatory Tetrad Analysis.

Version:

$Id: $Id

Author:

josephramsey

Constructor Summary

Constructors

Constructor	Description
DeltaSextadTest(DataSet dataSet)	Constructs a test using a given data set.
DeltaSextadTest(ICovarianceMatrix cov)	Constructs a test using the given covariance matrix.

Method Summary

Modifier and Type	Method	Description
double	calcChiSquare(Sextad[] sextads)	Takes a list of tetrads for the given data set and returns the chi square value for the test.
double	getPValue(Sextad... sextads)	Takes a list of tetrads for the given data set and returns the chi square value for the test.
List<Node>	getVariables()	Returns the variables of the data being used.
static DeltaSextadTest	serializableInstance()	Generates a simple exemplar of this class to test serialization.

Methods inherited from class java.lang.Object

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

Constructor Details

DeltaSextadTest

public DeltaSextadTest(DataSet dataSet)

Constructs a test using a given data set. If a data set is provided (that is, a tabular data set), fourth moment statistics can be calculated (p. 160); otherwise, it must be assumed that the data are multivariate Gaussian.

Parameters:

dataSet - The dataset to use.

DeltaSextadTest

public DeltaSextadTest(ICovarianceMatrix cov)

Constructs a test using the given covariance matrix. Fourth moment statistics are not caculated; it is assumed that the data are distributed as multivariate Gaussian.

Parameters:

cov - The covariance matrix to use.

Method Details

serializableInstance

public static DeltaSextadTest serializableInstance()

Generates a simple exemplar of this class to test serialization.

Returns:

This instance.

getPValue

public double getPValue(Sextad... sextads)

Takes a list of tetrads for the given data set and returns the chi square value for the test. We assume that the tetrads are non-redundant; if not, a matrix exception will be thrown.

Calculates the T statistic (Bollen and Ting, p. 161). This is significant if tests as significant using the Chi Square distribution with degrees of freedom equal to the number of nonredundant tetrads tested.

Parameters:

sextads - The sextads for which a p-value is needed.

Returns:

The p-value.

calcChiSquare

public double calcChiSquare(Sextad[] sextads)

Takes a list of tetrads for the given data set and returns the chi square value for the test. We assume that the tetrads are non-redundant; if not, a matrix exception will be thrown.

Calculates the T statistic (Bollen and Ting, p. 161). This is significant if tests as significant using the Chi Square distribution with degrees of freedom equal to the number of nonredundant tetrads tested.

Parameters:

sextads - The sextads for which a chi-square is needed

Returns:

The chi-square.

getVariables

public List<Node> getVariables()

Returns the variables of the data being used.

Returns:

This list.