# z-Score

A z-score, also called a "standard score," is the difference from the mean divided by the standard deviation.

Z-score is a college-level concept that would be first encountered in a probability and statistics course. It is an Advanced Placement Statistics topic.

### Prerequisites

Arithmetic Mean: | Arithmetic mean is a synonym for average, i.e., the sum of all values in a list divided by the number of values present. |

Standard Deviation: | The standard deviation is a statistic defined as the square root of the variance that measures how spread out a set of data is. |