statsmodels.sandbox.stats.runs.cochrans_q

statsmodels.sandbox.stats.runs.cochrans_q(x)[source]

Cochran’s Q test for identical effect of k treatments

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

Test that the probability of success is the same for each treatment. The alternative is that at least two treatments have a different probability of success.

Parameters:x (array_like, 2d (N,k)) – data with N cases and k variables
Returns:
  • q_stat (float) – test statistic
  • pvalue (float) – pvalue from the chisquare distribution

Notes

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