This is an approximate table of probabilities which relates dispersion units above or below the mean value to the total amount of the sample that is contained outside that region for values less than zero and inside the region for values greater than zero.

  • -3.0 .001
  • -2.5 .006
  • -2.2 .014
  • -2.0 .023
  • -1.8 .035
  • -1.6 .055
  • -1.4 .081
  • -1.2 .115
  • -1.0 .158
  • -0.8 .212
  • -0.6 .274
  • -0.4 .345
  • -0.2 .421
  • 0.0 .500
  • +0.2 .579
  • +0.4 .655
  • +0.6 .725
  • +0.8 .788
  • +1.0 .841
  • +1.2 .885
  • +1.4 .919
  • +1.6 .945
  • +1.8 .964
  • +2.0 .977
  • +2.2 .986
  • +2.5 .994
  • +3.0 .999

    The use of this table is not complicated. Here is how it works.

    Example 1:

    Example 2