# Notes

## Coefficient of Variation

The Coefficient of Variation explains the same thing which is explained by Standard Deviation. The advantage of using the coefficient of variation over Standard Deviation is that the Coefficient of variation is unit free. In more technical language, it is independent of scale whereas Standard Deviation is not independent of scale. It means one can …

## Standard Deviation of AP Series

Standard Deviation for an Arithmetic Progression (AP) Series can be calculated using a simple formula given below: [{sigma ^2} = frac{{left( {n + 1} right)left( {n – 1} right)}}{{12}}{d^2}] [sigma = sqrt {frac{{left( {n + 1} right)left( {n – 1} right)}}{{12}}} cdot d] where (d) is the common difference in a AP series.

## Different Formula for Variance & Standard Deviation

The formula for Variance: [{sigma ^2} = frac{{sumlimits_{i = 1}^n {{{left( {{X_i} – bar X} right)}^2}} }}{n}] It can also be written as follows: [{sigma ^2} = frac{{sum {left( {X_i^2 – 2bar X{X_i} + {{bar X}^2}} right)} }}{n}] [or,,,,{sigma ^2} = frac{{sum {X_i^2} – 2bar Xsum {{X_i}} + n{{bar X}^2}}}{n}] [or,,,,{sigma ^2} = frac{{sum {X_i^2} …

## Variance & Standard Deviation

Variance and Standard Deviation are the most frequently used measure of dispersion. Therefore, students of Econometrics should be well-acquainted with these concepts. Standard Deviation is the square root of Variance. So, we first need to know about Variance before we calculate the Standard Deviation. Variance is a measure of the average distance of observations from …

## Measures of Dispersion

Measures of Dispersion are the measure of the extent to which observations in a data set are close or far away from any given measure of central tendency. They are representative of homogeneity or heterogeneity of a distribution. The closer are the observations from their given central tendency, the more homogeneous is the distribution. The …

## Measures of Central Tendency (Averages)

Measures of Central Tendency, also called Averages, are representative of the entire distribution. It is the central value of a data set representing the whole data in a single number. There are five commonly used measures of central tendency: Arithmetic mean Median Mode Geometric mean Harmonic Mean Note: From the viewpoint of Econometrics, only Arithmetic …