Page 1 - lesson notes 62 xi MOD variance & Lorenz curve

SAI INTERNATIONAL SCHOOL

ECONOMICS

Class-XI

[STATISTICS FOR ECONOMICS]

CHAPTER -10

MEASURES OF DISPERSION

Module-62

TOPIC

Variance & Lorenz curve

SHORT NOTES

Although standard deviation is the most important tool to measure
dispersion, it is essential to know that it is derived from the variance.
Variance uses the square of deviations and is better than mean

deviation. However, since variance is based on the squares, its unit is
the square of the unit of items and mean in the series.

With this in mind, statisticians use the square root of the variance,

popularly known as standard deviation. Effectively, the square root of
the variance is the standard deviation. With the knowledge of
calculating standard deviation, we can easily calculate variance as the

square of standard deviation