Symbols:V

Variance

$\operatorname{var} \left({X}\right)$

Let $X$ be a discrete random variable.

Then the variance of $X$, written $\operatorname{var} \left({X}\right)$, is a measure of how much the values of $X$ varies from the expectation $E \left({X}\right)$, and is defined as:

$\operatorname{var} \left({X}\right) = E \left({\left({X - E \left({X}\right)}\right)^2}\right)$

That is: it is the expectation of the squares of the distances from the expectation.

The $\LaTeX$ code for $\operatorname{var} \left({X}\right)$ is \operatorname{var} \left({X}\right).