dev.nm.stat.test.rank.wilcoxon

Class WilcoxonSignedRank

java.lang.Object

dev.nm.stat.test.HypothesisTest

dev.nm.stat.test.rank.wilcoxon.WilcoxonSignedRank

public class WilcoxonSignedRank
extends HypothesisTest

The Wilcoxon signed rank test tests, for the one-sample case, the median of the distribution against a hypothetical median, and for the two-sample case, the equality of medians of groups. Unlike the Student's t-test, the Wilcoxon signed rank test does not assume any distribution of the population.

The R equivalent function is wilcox.test.

See Also:

• "Gibbons and Chakraborti, Nonparameric statistical inference (2003), Chapter 5.7, p.197."
• Wikipedia: Wilcoxon signed-rank test

Constructor Summary

Constructors

Constructor and Description
WilcoxonSignedRank(double[] sample) Perform the Wilcoxon Signed Rank test to test for the equality of medians.
WilcoxonSignedRank(double[] sample1, double[] sample2) Perform the Wilcoxon Signed Rank test to test for the equality of medians.
WilcoxonSignedRank(double[] sample1, double[] sample2, double mu, boolean isExact) Perform the Wilcoxon Signed Rank test to test for the equality of medians.
WilcoxonSignedRank(double[] sample, int mu) Perform the Wilcoxon Signed Rank test to test for the equality of medians.

Method Summary

Modifier and Type	Method and 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

WilcoxonSignedRank

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

Perform the Wilcoxon Signed Rank test to test for the equality of medians.

Parameters:

sample1 - sample 1

sample2 - sample 2

mu - the hypothetical median that the distribution is symmetric about

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

WilcoxonSignedRank

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

Perform the Wilcoxon Signed Rank test to test for the equality of medians.

Parameters:

sample1 - sample 1

sample2 - sample 2

WilcoxonSignedRank

public WilcoxonSignedRank(double[] sample,
                          int mu)

Perform the Wilcoxon Signed Rank test to test for the equality of medians.

Parameters:

sample - a sample

mu - the hypothetical median that the distribution is symmetric about

WilcoxonSignedRank

public WilcoxonSignedRank(double[] sample)

Perform the Wilcoxon Signed Rank test to test for the equality of medians.

Parameters:

sample - a sample

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.