Package dev.nm.stat.test.rank.wilcoxon

Class WilcoxonRankSum

java.lang.Object

dev.nm.stat.test.HypothesisTest

dev.nm.stat.test.rank.wilcoxon.WilcoxonRankSum

public class WilcoxonRankSum
extends HypothesisTest

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

Constructor Summary

Constructors

Constructor	Description
WilcoxonRankSum(double[] sample1, double[] sample2)	Perform the Wilcoxon Rank Sum test to test for the equality of means of two populations.
WilcoxonRankSum(double[] sample1, double[] sample2, double mu)	Perform the Wilcoxon Rank Sum test to test for the equality of means of two populations, or whether the means differ 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 populations, or whether the means differ 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 populations, or whether the means differ by an offset.

Method Summary

Modifier and Type	Method	Description
String	getAlternativeHypothesis()	Get the description of the alternative hypothesis.
String	getNullHypothesis()	Get a description of the null hypothesis.
double	leftOneSidedPvalue()	Get the left, one-sided p-value.
double	pValue()	Get the p-value for the test statistics.
double	rightOneSidedPvalue()	Get the right, one-sided p-value.
double	statistics()	Get the test statistics.

Methods inherited from class dev.nm.stat.test.HypothesisTest

isNullRejected, nGroups, nObs, oneSidedPvalue

Methods inherited from class java.lang.Object

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

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 populations, or whether the means differ 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 populations, or whether the means differ 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 populations, or whether the means differ by an offset. The exact distribution is used for sample size < 50.

Parameters:

sample1 - sample 1

sample2 - sample 2

mu - the hypothetical 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 populations.

Parameters:

sample1 - sample 1

sample2 - sample 2

Method Detail

getNullHypothesis

public 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 String getAlternativeHypothesis()

Description copied from class: HypothesisTest

Get the description of the alternative hypothesis.

Specified by:

getAlternativeHypothesis in class HypothesisTest

Returns:

the alternative hypothesis description

See Also:

Wikipedia: Alternative hypothesis

statistics

public double statistics()

Description copied from class: HypothesisTest

Get the test statistics.

Specified by:

statistics in class HypothesisTest

Returns:

the test statistics

See Also:

Wikipedia: Test statistic

pValue

public double pValue()

Description copied from class: HypothesisTest

Get the p-value for the test statistics.

Specified by:

pValue in class HypothesisTest

Returns:

the p-value

See Also:

Wikipedia: P-value

rightOneSidedPvalue

public double rightOneSidedPvalue()

Get the right, one-sided p-value.

Returns:

the right, one-sided p-value.

leftOneSidedPvalue

public double leftOneSidedPvalue()

Get the left, one-sided p-value.

Returns:

the left, one-sided p-value.