Probability & Statistics Symbols

Probability & Statistics

Symbols used when analyzing data and chance.

Symbol	Name	Meaning / Usage
$P(A)$	Probability of A	The chance that event A will occur ( $0 \leq P(A) \leq 1$ ).
$\mu$	Mu	Population Mean (average) ( $\mu = \frac{1}{n}\sum_{i=1}^{n} x_i$ ).
$\sigma$	Sigma (lowercase)	Standard Deviation ( $\sigma = \sqrt{\frac{1}{n}\sum_{i=1}^{n}(x_i - \mu)^2}$ ).
$\bar{x}$	x-bar	Sample Mean ( $\bar{x} = \frac{1}{n}\sum_{i=1}^{n} x_i$ ).
$\chi^2$	Chi-Squared	Distribution used in hypothesis testing ( $\chi^2$ test).