zA zB zC zD zE zF   ybar      s2
   1 -1  1 -1 -1 -1  0.9800  0.021400
  -1 -1  1 -1  1  1  1.5450  0.004967
   1  1 -1 -1 -1  1  1.1300  0.042867
  -1  1 -1 -1  1 -1  1.7375  0.005825
  -1 -1 -1  1 -1  1  1.4900  0.006467
   1 -1 -1  1  1 -1  0.8350  0.010700
  -1  1  1  1 -1 -1  2.1750  0.017633
   1  1  1  1  1  1  1.4475  0.002358