Python statistics variance()

The statistics.variance function in Python's statistics module calculates the variance of a given set of numbers. Variance measures how far a set of numbers are spread out from their average value. It provides an insight into the degree of variation or dispersion within a dataset.

Table of Contents

1. Introduction
2. statistics.variance Function Syntax
3. Examples
   • Basic Usage
   • Variance of a List of Numbers
   • Variance of a Tuple of Numbers
   • Handling Different Types of Numeric Data
4. Real-World Use Case
5. Conclusion

Introduction

The statistics.variance function is part of the statistics module, which provides functions for mathematical statistics of numeric data. The variance is useful for understanding the variability of a dataset. It is the average of the squared differences from the mean.

statistics.variance Function Syntax

Here's how you use the statistics.variance function:

import statistics

variance_value = statistics.variance(data)

Parameters:

• data: A sequence or iterable of numeric data (list, tuple, etc.).

Returns:

• The variance of the given data.

Raises:

• StatisticsError: If data has fewer than two values.

Examples

Basic Usage

Calculate the variance of a list of numbers.

import statistics

data = [1, 2, 3, 4, 5]
variance_value = statistics.variance(data)
print(f"Variance: {variance_value}")

Output:

Variance: 2.5

Variance of a List of Numbers

Calculate the variance of a list of integers.

import statistics

numbers = [10, 20, 30, 40, 50]
variance_value = statistics.variance(numbers)
print(f"Variance of numbers: {variance_value}")

Output:

Variance of numbers: 250

Variance of a Tuple of Numbers

Calculate the variance of a tuple of floats.

import statistics

numbers = (1.5, 2.5, 3.5, 4.5, 5.5)
variance_value = statistics.variance(numbers)
print(f"Variance of numbers: {variance_value}")

Output:

Variance of numbers: 2.5

Handling Different Types of Numeric Data

Calculate the variance of a mixed list of integers and floats.

import statistics

numbers = [1, 2.5, 3, 4.5, 5]
variance_value = statistics.variance(numbers)
print(f"Variance of numbers: {variance_value}")

Output:

Variance of numbers: 2.575

Real-World Use Case

Calculating the Variability in Sales Data

Calculate the variance of monthly sales data to understand the variability in sales performance.

import statistics

monthly_sales = [25000, 27000, 24000, 26000, 30000, 28000, 29000, 31000, 22000, 23000, 25000, 27000]
variance_sales = statistics.variance(monthly_sales)
print(f"Variance of monthly sales: {variance_sales}")

Output:

Variance of monthly sales: 7719696.96969697

Conclusion

The statistics.variance function is a simple and effective way to calculate the variance of a set of numbers in Python. It is useful for understanding the variability and dispersion of a dataset. This function makes it easy to determine the variance, which is a common requirement in various fields such as finance, science, and engineering.