Q.Which one of the following is a RELATIVE measure of dispersion?

A relative measure of dispersion is unit-free (a ratio or percentage); an absolute measure carries the data's units. …

A relative measure of dispersion is a pure number with no units — formed by dividing an absolute measure by an average — and it is what allows two data sets to be compared.

• (a) Range $= L - S$: carries the data's units (e.g. rupees). Absolute.
• (b) Standard deviation $\sigma$: also in the data's units. Absolute.
• (d) Quartile deviation $= \tfrac{Q_3 - Q_1}{2}$: in the data's units. Absolute. …

Confusing the standard deviation itself with its relative form — the standard deviation is absolute; only when it is divided by the mean (and $\times 100$) does it become the RELATIVE coefficient of variati …