NORMRULE

When is a variable normally distributed? One way to tell is with the following (from page 104-105 of ES7):

Empirical Rule
If a variable is normally distributed, then:
within one standard deviation of the mean there will be approximately 68% of the data;
within two standard deviations of the mean there will be approximately 95% of the data; and
within threestandard deviations of the mean there will be approximately 99.7% of the data.

Keywords

normal distribution

Description

On pgs. 104-107 in ES7 an empirical rule is given for checking normality. To check a set of values with this rule, use the NORMRULE template. The template as one data column, SCORE, and three calculated columns.

NORMRULE

The formula for the column ~95% is as follows (and the others are similar).

The formulas calculate 0/1 values according to whether the original variable is within 1, 2, or 3 standard deviations.


Use of Normrule