code: private boolean rule7(double sample) {
          if (!hasMean()) {
              return false;
          }
  
          if (sample == mean.getResult()) {
              rule7Count = 0;
              return false;
          }
  
          if (Math.abs(sample - mean.getResult()) <= oneDeviation) {
              ++rule7Count;
          } else {
              rule7Count = 0;
          }
  
          return rule7Count >= 15;
      }
docs: a very steady metric. Minimally, I have taken away the flat-line case where all samples are the mean.