absolute deviation

this is the difference between one numerical value and another numerical value. Negative values are ignored as we are simply measuring the distance between the two numbers. Most commonly, absolute deviation in statistics is the difference between a score and the mean (or sometimes median) of the set of scores. Thus, the absolute deviation of a score of 9 from the mean of 5 is 4. The absolute deviation of a score of 3 from the mean of 5 is 2 (Figure A.1). One advantage of the absolute deviation over deviation is that the former totals (and averages) for a set of scores to values other than 0.0 and so gives some indication of the variability of the scores.

Figure A.1 Absolute deviations