Statistics 


Skewness is the degree of asymmetry, or departure from symmetry, of a distribution.
For skewness distribution, the mean tends to lie on the same side of the mode as the longer tail. In many books measure of skewness is denoted by , J or S_{k}. Different formulae for measuring skewness are: i) Bowley's formula for measuring skewness in terms of quartiles is: ii) Kelley gave the formula in terms of percentiles and deciles. Kelley's absolute measures os skewnes are: S_{k}=P_{90}+P_{10}2P_{50}= D_{9}+D_{1}2D_{5} These formulae are not practically used. Instead, it is measured as coefficient of skewness which is given as: Kelly's formulae are seldom used. iii) Karl Pearson's measure of skewness: iv) Karl pearson's formulae for a wide class of frequency distributions in terms of moments is gives only the measure of skewness but not the direction of skewness. So another measure is defined as: How to interpret the value of measure of skewness:
Calculate the coefficient of skewness of the following data by using Karl Pearson's method. 2 3 3 4 4 6 6 Step 1. Find the mean: Step 2. Find the standard deviation:
Then Step 3. Find the coefficient of skeness: (negative skewness) Properties:
