---
title: "system.math.populationVariance"
description: "Given a sequence of values, returns the population variance."
---

# system.math.populationVariance

> Given a sequence of values, returns the population variance.

This function is used in **Python Scripting**.

## Description
Given a sequence of values, returns the population variance. Population variance calculates how values in a dataset are spread out from their average value.

Returns NaN (Not a Number) if passed an empty sequence.

## Client Permission Restrictions
This scripting function has no [Client Permission](../../../ignition-modules/vision/vision-project-properties/vision-project-properties.md#vision-permissions-properties) restrictions.

## Syntax
`system.math.populationVariance(values)`

### Parameters
Type | Parameter | Description 
------- | ------- | ------
List[Float] | `values` | A sequence of numerical values. Accepts both integers and floats. The sequence may not contain None type values. However, passing a None type object instead of a sequence of numerical values will return NaN.

### Returns
**Float** - The population variance, or NaN if the input was empty or null.

### Scope
Gateway, Vision Client, Perspective Session

## Code Examples
```python title="Example #1 - Calculating Population Variance"
# Create a list of values.
values = [3.5, 5.6, 7.8, 7.4, 3.8]
  
# Print the resulting value.
print system.math.populationVariance(values)
```