Explain merits and demerits of quartile Deviation.
Merits : 1. It is easy understand and to calculate.
2. It is unaffected by the extreme values.
3. It is quite satisfactory when only the middle half of the group is dealt with.
Demerits : 1. It ignores 50 per cent of the extreme items.
2. It is not capable of algebraic treatment.
3. This is not useful when extreme items are to be given special height.