dispersion

How dispersed, or spread out, scores are.

It is useful to know how dispersed a #population of scores are. If you are told that your cholesterol is 10 points higher than average for your age, is this difference a lot? Are you an extreme case, or still within the bounds of normality? Dispersion allows meaningful interpretation of scores. Without some idea of dispersion, we cannot know if a score is an outlier. The most commonly used measures of disperson are standard deviation, variance, and range.