docs: public static double sigLevelByApproxRand(double[] A, double[] B, int iterations) {
      if (A.length == 0)
        throw new IllegalArgumentException("Input arrays must not be empty!");
      if (A.length != B.length)
        throw new IllegalArgumentException("Input arrays must have equal length!");
      if (iterations <= 0)
        throw new IllegalArgumentException("Number of iterations must be positive!");
      double testStatistic = absDiffOfMeans(A, B, false); // not randomized
      int successes = 0;
      for (int i = 0; i < iterations; i++) {
        double t =  absDiffOfMeans(A, B, true); // randomized
        if (t >= testStatistic) successes++;
      }
      return (double) (successes + 1) / (double) (iterations + 1);
    }