The z-score, also known as a standard score, is used in statistics. It measures the number of standard deviations of a specific number.

To calculate z-score you can use the following formula.

z-score = (x – μ) / σ

x – value

μ – mean

σ – standard deviation

Let’s take a look at the following example. This site iqtestprep.com shows the IQ score of famous people.

I chose just a few examples to illustrate how you can calculate the mean, standard deviation, and z-score.

You can copy the following example.

First Name | Last Name | IQ |

Muhammad | Ali | 78 |

Rowan | Atkinson | 178 |

Kobe | Bryant | 114 |

Warren | Buffet | 145 |

Miley | Cyrus | 120 |

David | Duchovny | 147 |

Thomas | Edison | 145 |

Jodie | Foster | 132 |

Ariana | Grande | 105 |

Stephen | Hawking | 160 |

Charles | Manson | 109 |

OJ | Simpson | 89 |

## Calculating standard deviation in Excel

- Calculate the mean for the IQ scores, by using the following formula
**=AVERAGE(C2:C13)**and call it**mean**.

- Calculate the standard deviation with this formula:
**=STDEVPA(C2:C13)**and call it**stdev**. - In cell
**D2**, calculate the z-score for the first IQ:**=STANDARDIZE(C2, mean, stdev)**. - Use autofill to calculate the remaining z-scores.

This is the result of our calculations.