Summarizing data from a measurement variable requires a number that represents the "middle" of a set of numbers along with a measure of the "spread" of the numbers. You use a statistic of dispersion t...Summarizing data from a measurement variable requires a number that represents the "middle" of a set of numbers along with a measure of the "spread" of the numbers. You use a statistic of dispersion to give a single number that describes how compact or spread out a set of observations is. Although statistics of dispersion are usually not very interesting by themselves, they form the basis of most statistical tests used on measurement variables.
