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Posted to issues@commons.apache.org by "Danaja Thiyunuwan Maldeniya (JIRA)" <ji...@apache.org> on 2015/01/20 06:41:34 UTC

[jira] [Created] (MATH-1197) Incorrect Kolmogorov–Smirnov Statistic for two samples

Danaja Thiyunuwan Maldeniya created MATH-1197:
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             Summary: Incorrect Kolmogorov–Smirnov Statistic for two samples 
                 Key: MATH-1197
                 URL: https://issues.apache.org/jira/browse/MATH-1197
             Project: Commons Math
          Issue Type: Bug
    Affects Versions: 3.4.1
         Environment: Ubuntu 14.04
            Reporter: Danaja Thiyunuwan Maldeniya


kolmogorovSmirnovTest(double[],double[]) against the samples given below gives 5.699107852308316E-12 instead of 0.9793 (approx.) Traced the issue to kolmogorovSmirnovStatistic(double[],double[]) which gives 0.49507389162561577 instead of 0.064 (verified with ks.test in R and JDistlib)

  double[] x = {0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,2.202653,2.202653,2.202653
                ,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653
                ,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653
                ,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,3.181199,3.181199,3.181199,3.181199,3.181199,3.181199,3.723539
                ,3.723539,3.723539,3.723539,4.383482,4.383482,4.383482,4.383482,5.320671,5.320671,5.320671,5.717284,6.964001,7.352165
                ,8.710510,8.710510,8.710510,8.710510,8.710510,8.710510,9.539004,9.539004, 10.720619, 17.726077, 17.726077, 17.726077, 17.726077
                ,22.053875 ,23.799144 ,27.355308 ,30.584960 ,30.584960 ,30.584960, 30.584960, 30.751808};



         double[] y = {0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                 ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                 ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000
                 ,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,2.202653
                 ,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,2.202653,3.061758,3.723539,5.628420,5.628420,5.628420,5.628420
                 ,5.628420,6.916982,6.916982,6.916982, 10.178538, 10.178538, 10.178538, 10.178538, 10.178538 };



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