User Guide

317
Descriptives
Descriptive
s Options
Figure 14-2
Descriptives O ptions dialog box
Mean and Sum. The mean, or arithmetic average, is displayed by default.
Dispersion. Statistics that measure the spread or variation in the data include the
standard deviation, variance, range, minimum, maximum, and standard error of
the mean.
 Standard deviation. A measure of dispersion around the mean. In a normal
distribution, 68% of cases fall within one standard deviation of the mean and
95% of cases fall within two standard deviations. For example, if the mean
age is 45, with a standard deviation of 10, 95% of the cases would be between
25and65inanormaldistribution.
 Variance. A measure of dispersion around the mean, equal to the sum of squared
deviations from the mean divided by one less than the number of cases. The
variance is measured in units that are thesquareofthoseofthevariableitself.
 Range. The difference between the largest and smallest values of a numeric
variable; the maximum minus the minimum.