(i) Meaning, types and Objectives of Skewness
Meaning. Skewness means asymmetricity of the distribution of a statistical series.It is opposite to the symetrical nature of a series. In a symmetric series, the following characteristics are found:
Characteristic of a Symmetric Series
- The values of the series when plotted on a graph paper give a bell shaped curve as under:
- The values of Mean, Median and Mode are identical.
- Both the extreme quartiles i.e. Q3 are equidistant from the Median i.e. (Q3 – M) = (M – Q1).
- Both the extreme Percentiles, and Deciles are equidistant from the Median.
i.e. (P90 – M) = (M – P10), and
(D9 – M ) = (M – D1)
- The sum of the positive diviations from Median is equal to the sum of the negative deviations from Median i.e. ∑(X-M) =0
- The frequencies are equally distributed at the points of equal deviations from Mode.
- B1 (Beta one) is equal to zero.
- B2 (Beta two) is equal to 3.
- Y1 (Gamma one) is equal to zero.