User Guide

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Chapter 17
are longer than those of a normal distribution; a negative value for kurtosis indicates
shorter tails (becoming like those of a box-shaped uniform distribution).
Standard Er
ror of Skewness.
The ratio of skewness to its standard error can be used
as a test of normality (that is, you can reject normality if the ratio is less than -2 or
greater than +2). A large positive value for skewness indicates a long right tail; an
extreme neg
ative value, a long left tail.
Sum. The sum or total of the values, across all cases with nonmissing values.
Variance. A measure of dispersion around the mean, equal to the sum of squared
deviation
s from the mean divided by one less than the number of cases. The variance
is measured in units that are the square of those of the variable itself.