Symbols:Greek/Sigma/Standard Deviation

Standard Deviation

$\sigma_X$

Let $X$ be a random variable.

Then the standard deviation of $X$, written $\sigma_X$ or $\sigma$, is defined as the principal square root of the variance of $X$:

$\sigma_X := \sqrt {\var X}$

The $\LaTeX$ code for \(\sigma_X\) is \sigma_X .

Sources

• 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): sigma: 4.
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): sigma