** Absolute and Relative Measures of Deviation:** We have seen that there are four measures of deviation i.e. Range, Quartile deviation, Mean deviation, and Standard deviation. All these are called absolute measures of dispersion because they are expressed in the units in which the data are expressed. They are useful to measure the variability of a given group. These absolute measures of deviation are not useful for comparison. To answer this question, we calculate the ratio of the measure of dispersion to some other convenient number. This ratio is called the relative measure of dispersion and is a pure number free from the unit. They are also called the coefficient of dispersion. If the relative measure of the dispersion of one group is higher than the other, we infer that the group has more variability than the other. The absolute and relative measures of dispersion are given in Table.

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