What is meant by mean deviation? What are the methods to calculate it? Give its merits and demerits.

What is meant by mean deviation? What are the methods to calculate it?

1.	What is meant by mean deviation? What are the methods to calculate it? Give its merits and demerits.
Answer» Solution :MEAN deviation is the arithmetic average of the deviations of all the values taken from some average value (mean, MEDIAN, mode) of the series, ignoring signs ( + or - ) of deviations. Merits :- 1. SImple. 2. BASED on all values. 3. LESS effect on EXTREME Values. Demerits :- 1. Inaccuracy. 2. Not capable of Algebraic Treatment. 3. Unreliable.