# ZTEST

## Content

This function returns the significance value of a z-test. The z-test generates a standard score for x with respect to the set of data and returns the two-tailed probability for the normal distribution.

## Syntax

`ZTEST(array, x, [sigma])`

## Arguments

This function has these arguments:

| Argument | Description |
| -------- | ----------- |
| *array* | [Required] Array of data to test |
| *x* | [Required] Value at which to test |
| *sigma* | [Optional] Known standard deviation for the population; if omitted, the calculation uses the sample standard deviation |

## Remarks

If sigma is not specified, the calculated standard deviation of the data in the array is used.
The equation for calculating the z-test is as follows, where *n* is the number of data points.
![](https://cdn.mescius.io/document-site-files/images/8d606653-16a0-474d-b9dc-e2b4d01c2446/images/Func-ZTEST.png)

## Examples

`ZTEST(A2:D12,40,0.877)`
`ZTEST(R2C1:R12C4,2)`
`ZTEST({5,10,15,12,11,8,16,7},10)` gives the result 0.355512703503418
`ZTEST({5,10,15,12,11,8,16,7},10,3)` gives the result 0.318675944098237