Measures of Dispersion

Things to remember

1. The measures of any set of data show the range of the data or the amount of variation is known as variability or dispersion.
2. The difference between the highest and the lowest values of the variable of any set of data is called the range.
3. The difference between the first quartile (Q₁) and the third quartile (Q₃) is known as the interquartile range. The half of the interquartile range is called semi- interquartile range or quartile deviation.
4. Coefficient of Range = \(\frac{L - S}{L + S}\)
5. Quartile deviation (Q.D.) = \(\frac {Q_3 - Q_1}2\)