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

java.lang.Object
  com.numericalmethod.suanshu.stats.test.HypothesisTest
      com.numericalmethod.suanshu.stats.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 median 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

Field Summary

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

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

java.lang.String	alternativeHypothesis() Get a description of the alternative hypothesis.
java.lang.String	nullHypothesis() Get a description of the null hypothesis.

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

oneSidedPvalue, pValue, rejectNull, testStatistics

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

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

nullHypothesis

public java.lang.String nullHypothesis()

Description copied from class: HypothesisTest

Get a description of the null hypothesis.

Specified by:

nullHypothesis in class HypothesisTest

Returns:

the null hypothesis description

See Also:

Wikipedia: Null hypothesis

alternativeHypothesis

public java.lang.String alternativeHypothesis()

Description copied from class: HypothesisTest

Get a description of the alternative hypothesis.

Specified by:

alternativeHypothesis in class HypothesisTest

Returns:

the alternative hypothesis description

See Also:

Wikipedia: Alternative hypothesis