# z-Score

Last Updated: 2021-11-19

## Formula

$z = { x - \mu \over \delta}$

where $\mu$ is the **mean** of the population, $\delta$ is the **standard deviation** of the population.

## Alternative

**mean** and **stdDev** are strongly affected by outliers, another way is:

- mean replaced by median
- stdDev replaced by absolute standard deviation P65