Q.From the following the one which is not a positional measure, is :

Deciles divide a distribution into ten equal parts.

Partition values divide an ordered distribution into equal groups:

• Quartiles ($Q_1,Q_2,Q_3$) $\rightarrow$ 4 equal parts.
• Deciles ($D_1,D_2,\ldots,D_9$) $\rightarrow$ 10 equal parts. …

Quartile deviation is a dispersion measure, so it is the odd one out.

A measure of central value (central tendency / positional average) points to a representative or locating value of the data:

• Median — the middle value,
• Mode — the most frequent value,
• Quartile — a positional value dividing the data into four parts. …

Positional measures are located by rank (Median, Quartiles); Standard deviation is a computed average measure — the odd one out.

Positional measures are found by their place in the arranged data:

• Median — the middle positional value,
• Quartiles — positional values at the quarter points. …

Three quartiles ⇒ four parts.

Quartiles are positional values that split the arranged data at the $25\%$, $50\%$ and $75\%$ points. These three cut-points $Q_1, Q_2, Q_3$ divide the whole distribution into $4$ equal p …

Median $=P_{50}=Q_2=D_5$.

Percentiles divide an ordered distribution into 100 equal parts. The $P_{50}$ value has 50% of the data below it — which is precisely the definition of the median (and equally th …

Correct option: (b) Quartiles.

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