Variance

Variance of a population refers to the average squared delta from the mean. Though variance is a step in the calculation of Standard Deviation, it's typically written as standard deviation squared: $\sigma^2$

$\sigma^2 = \frac{\sum(x-\mu)^2}{n}$

• Where $\mu$ refers to the mean of the population.
• $(x - \mu)^2$ is the squared difference from the mean.
• $\sum(x-\mu)^2$ is the sum of the squared differences across all $n$ values.

Typically variance is a step to calculating the standard deviation.