com.numericalmethod.suanshu.stats.test.rank.wilcoxon

Class WilcoxonRankSum

java.lang.Object

com.numericalmethod.suanshu.stats.test.HypothesisTest

com.numericalmethod.suanshu.stats.test.rank.wilcoxon.WilcoxonRankSum

All Implemented Interfaces:

java.io.Serializable

public class WilcoxonRankSum
extends HypothesisTest

The Wilcoxon rank sum test tests for the equality of means of two population, or whether the means differs by an offset. That is, it tests the null hypothesis that the distribution x - y is symmetric about mu.

This is also called the Mann–Whitney–Wilcoxon, Mann-Whitney-U, or Wilcoxon–Mann–Whitney test.

The R equivalent function is wilcox.test.

See Also:

Wikipedia: Mann–Whitney U, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
double	pValue1SidedGreater right, one-sided p-value
double	pValue1SidedLess left, one-sided p-value

Fields inherited from class com.numericalmethod.suanshu.stats.test.HypothesisTest

k, N, pValue, testStatistics

Constructor Summary

Constructors

Constructor and Description
WilcoxonRankSum(double[] sample1, double[] sample2) Perform the Wilcoxon Rank Sum test to test for the equality of means of two population.
WilcoxonRankSum(double[] sample1, double[] sample2, double mu) Perform the Wilcoxon Rank Sum test to test for the equality of means of two population, or whether the means differs by an offset.
WilcoxonRankSum(double[] sample1, double[] sample2, double mu, boolean isExact) Perform the Wilcoxon Rank Sum test to test for the equality of means of two population, or whether the means differs by an offset.
WilcoxonRankSum(double[] sample1, double[] sample2, double mu, boolean isExact, boolean isCorrected) Perform the Wilcoxon Rank Sum test to test for the equality of means of two population, or whether the means differs by an offset.

Method Summary

Modifier and Type	Method and Description
java.lang.String	getAlternativeHypothesis() Get a description of the alternative hypothesis.
java.lang.String	getNullHypothesis() Get a description of the null hypothesis.

Methods inherited from class com.numericalmethod.suanshu.stats.test.HypothesisTest

isNullRejected, oneSidedPvalue, pValue, statistics

Methods inherited from class java.lang.Object

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

Field Detail

pValue1SidedLess

public final double pValue1SidedLess

left, one-sided p-value

pValue1SidedGreater

public final double pValue1SidedGreater

right, one-sided p-value

Constructor Detail

WilcoxonRankSum

public WilcoxonRankSum(double[] sample1,
                       double[] sample2,
                       double mu,
                       boolean isExact,
                       boolean isCorrected)

Perform the Wilcoxon Rank Sum test to test for the equality of means of two population, or whether the means differs by an offset.

Parameters:

sample1 - sample 1

sample2 - sample 2

mu - the hypothetical location that the sample1 - sample2 is symmetric about

isExact - true if to use the exact distribution; otherwise, normal approximation is used

isCorrected - true if to use the continuity correction for the normal distribution; otherwise, standard normal approximation is used

WilcoxonRankSum

public WilcoxonRankSum(double[] sample1,
                       double[] sample2,
                       double mu,
                       boolean isExact)

Perform the Wilcoxon Rank Sum test to test for the equality of means of two population, or whether the means differs by an offset.

Parameters:

sample1 - sample 1

sample2 - sample 2

mu - the hypothetical location that the sample1 - sample2 is symmetric about

isExact - true if to use the exact distribution; otherwise, normal approximation is used

WilcoxonRankSum

public WilcoxonRankSum(double[] sample1,
                       double[] sample2,
                       double mu)

Perform the Wilcoxon Rank Sum test to test for the equality of means of two population, or whether the means differs by an offset.

The exact distribution is used for sample size < 50.

Parameters:

sample1 - sample 1

sample2 - sample 2

mu - the hypotheical location that the sample1 - sample2 is symmetric about

WilcoxonRankSum

public WilcoxonRankSum(double[] sample1,
                       double[] sample2)

Perform the Wilcoxon Rank Sum test to test for the equality of means of two population.

Parameters:

sample1 - sample 1

sample2 - sample 2

Method Detail

getNullHypothesis

public java.lang.String getNullHypothesis()

Description copied from class: HypothesisTest

Get a description of the null hypothesis.

Specified by:

getNullHypothesis in class HypothesisTest

Returns:

the null hypothesis description

See Also:

Wikipedia: Null hypothesis

getAlternativeHypothesis

public java.lang.String getAlternativeHypothesis()

Description copied from class: HypothesisTest

Get a description of the alternative hypothesis.

Specified by:

getAlternativeHypothesis in class HypothesisTest

Returns:

the alternative hypothesis description

See Also:

Wikipedia: Alternative hypothesis