# zscore

Z-score (aka standard score) indicates how many standard
deviations an element is from the mean.
A z-score can be calculated from the following formula:
`z = (X - μ) / σ`

- z-score from percent:
`scipy.stats.norm.ppf(fraction of 1)`

- percent from z-score:
`scipy.stats.norm.cdf(z_score)`