SciPy

This is documentation for an old release of SciPy (version 0.17.1). Read this page in the documentation of the latest stable release (version 1.15.1).

scipy.stats.tiecorrect

scipy.stats.tiecorrect(rankvals)

Tie correction factor for ties in the Mann-Whitney U and Kruskal-Wallis H tests.

Parameters:

rankvals : array_like

A 1-D sequence of ranks. Typically this will be the array returned by stats.rankdata.

Returns:

factor : float

Correction factor for U or H.

See also

rankdata
Assign ranks to the data
mannwhitneyu
Mann-Whitney rank test
kruskal
Kruskal-Wallis H test

References

[R445]Siegel, S. (1956) Nonparametric Statistics for the Behavioral Sciences. New York: McGraw-Hill.

Examples

>>>
>>> from scipy.stats import tiecorrect, rankdata
>>> tiecorrect([1, 2.5, 2.5, 4])
0.9
>>> ranks = rankdata([1, 3, 2, 4, 5, 7, 2, 8, 4])
>>> ranks
array([ 1. ,  4. ,  2.5,  5.5,  7. ,  8. ,  2.5,  9. ,  5.5])
>>> tiecorrect(ranks)
0.9833333333333333