statsmodels.stats.contingency_tables.cochrans_q¶

statsmodels.stats.contingency_tables.cochrans_q(x, return_object=True)[source]

Cochran’s Q test for identical binomial proportions.

Parameters: x (array_like, 2d (N, k)) – data with N cases and k variables return_object (boolean) – Return values as bunch instead of as individual values. Returns a bunch containing the following attributes, or the individual values according to the value of return_object. statistic (float) – test statistic pvalue (float) – pvalue from the chisquare distribution

Notes

Cochran’s Q is a k-sample extension of the McNemar test. If there are only two groups, then Cochran’s Q test and the McNemar test are equivalent.

The procedure tests that the probability of success is the same for every group. The alternative hypothesis is that at least two groups have a different probability of success.

In Wikipedia terminology, rows are blocks and columns are treatments. The number of rows N, should be large for the chisquare distribution to be a good approximation.

The Null hypothesis of the test is that all treatments have the same effect.

References

http://en.wikipedia.org/wiki/Cochran_test SAS Manual for NPAR TESTS