Definition:Skewness

Definition
Skewness is a measure of the asymmetry of a probability distribution about its mean.

Let $X$ be a random variable with mean $\mu$ and standard deviation $\sigma$.

Then the skewness of $X$, usually denoted $\gamma_1$, is defined as:


 * $\gamma_1 = \expect {\paren {\dfrac {X - \mu} \sigma}^3}$

where $\expect X$ denotes the expectation of $X$.