Variance and Standard Deviation

Variance

In probability theory and statistics, variance is the expectation of the squared deviation of a random variable from its mean.

s2 stands for the variance

The formula means that from every
observation () you have to subtract the mean
value of that variable (̅). Next, you have to
square all these values and add them up

Advantage

They take into account all the values of a variable.

Standard Deviation

The standard deviation is the measure of dispersion used most often

A quantity calculated to indicate the extent of deviation for a group as a whole.

Letter "s" Stands for Standard Deviation

It's the square root of "s2"

Purpose

Useful for

Observing that The larger the variance, the larger
the variability.