5.4 Mean Deviation
Average deviations ( mean deviation ) is the average amount of variations (scatter) of the items in a distribution from either the mean or the median or the mode, ignoring the signs of these deviations by Clark and Senkade.
Individual Series
Steps : (1) Find the mean or median
or mode of the given series.
(2) Using and one of three, find the deviations ( differences ) of the items of the series from them.
i.e. xi  x, xi  Me and xi  Mo.
Me = Median and Mo = Mode.
(3) Find the absolute values of these deviations i.e. ignore there positive (+) and negative () signs.
i.e.  xi  x  ,  xi  Me  and xi  Mo .
(4) Find the sum of these absolute deviations.
i.e. S  xi  x  + , S  xi  Me  , and S  xi  Mo  .
(5) Find the mean deviation using the following formula.
Note that :
(i) generally M. D. obtained from the median is the best for the practical purpose.
(ii) coefficient of M. D. =
Example Calculate Mean deviation and its
coefficient for the following salaries:
$ 1030, $ 500, $ 680, $ 1100, $ 1080, $ 1740. $ 1050, $ 1000, $ 2000, $ 2250, $ 3500 and $ 1030.
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