Database Reference
In-Depth Information
A3.4.3 Sample Calculations
Figure
A3-4
provides a summary of the formulas that are often used in performing
calculations about samples:
Figure A3-4.
Formulas for Sample Calculations
These formulas are best explained by examining the normal distribution curve
(Figure
A3-5
). From the curve, observe that:
•
Prob (-1 <= Z <= 1) = 68.27%
•
Prob (-2 <= Z <= 2) = 95.25%
•
Prob (-3 <= Z <= 3) = 99.73%
