Rethinking the 80/20 Rule in Software Development

Many apply the Pareto principle to software development, but how useful is this really?

Photo by Austin Distel on Unsplash

People often try to apply the 80/20 rule to software development projects.

This can take many forms such as:

• 80% of the work takes 20% of the time
• 20% of users will find 80% of the bugs
• 80% of users use only 20% of the features
• 80% of changes are made in 20% of the code

And so on…

The Pareto Principle

All of these statements are based on a thing called the Pareto Principle. This generalizes to:

“80% of consequences come from 20% of causes.“ — Investopedia

The rule was named after 19th-century Italian economist Vilfredo Pareto who noticed that 80% of the land in Italy was owned by 20% of the population.

Pareto in Software

Numerous studies have been conducted into the application of the Pareto Principle in software development, and they all conclude different things.