Package edu.cmu.tetrad.search.utils

Class DeltaTetradTest

java.lang.Object

edu.cmu.tetrad.search.utils.DeltaTetradTest

public class DeltaTetradTest
extends Object

Implements a test for simultaneously zero tetrads in Bollen, K. (1990). "Outlier screening and distribution-free test for vanishing tetrads." Sociological Methods and Research 19, 80-92 and Bollen and Ting, Confirmatory Tetrad Analysis.

Version:

$Id: $Id

Author:

josephramsey

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
double	calcChiSquare(Tetrad... tetrads)	Takes a list of tetrads for the given data set and returns the chi square value for the test.
double	getPValue()	getPValue.
double	getPValue(Tetrad... tetrads)	Returns a p-value for the given list of tetrad.

Methods inherited from class java.lang.Object

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

Constructor Details

DeltaTetradTest

public DeltaTetradTest(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.

DeltaTetradTest

public DeltaTetradTest(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 covaraince matrix to use.

Method Details

calcChiSquare

public double calcChiSquare(Tetrad... tetrads)

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:

tetrads - The tetrads for which a chi-square is needed.

Returns:

a double

getPValue

public double getPValue()

getPValue.

Returns:

the p value for the most recent test.

getPValue

public double getPValue(Tetrad... tetrads)

Returns a p-value for the given list of tetrad.

Parameters:

tetrads - The tetrad for which a p-vaue is needed.

Returns:

The p-value.