# DoodleMaths and the 80/20 rule

A guest blog by Bill Smith, a PhD student, investigating the link between DoodleMaths and the 80/20 rule.

## What is the 80/20 rule?

The 80/20 rule is a popular rule that links ‘outputs’ to the ‘inputs’ of a system.

• ‘Outputs’ are measurable properties or events, such as purchases made, goals scored in a sporting match, or food production.
• ‘Inputs’ are known to affect the outputs, and include items for sale, players fielded, or plots of land.

If a system follows this rule, then 80% of the outputs are due to 20% of the inputs.

This rule was originally created on the observation that 80% of the land in Italy was owned by 20% of the population.

Since then, it has been widely used to describe a range of phenomena, including wealth distribution, super spreading events and studying materials for exams.

## Investigating DoodleMaths and the 80/20 rule

Here at DoodleLearning, we were curious as to whether this rule would hold true for the number of stars earned by children using DoodleMaths.

To investigate this rule, we ranked all of the children using Doodle by the number of stars they’d earned. We then split this ranking into ten groups, with the results shown below.

Those in the cyan group (the top group) earned more stars than 90% of the other children; their stars accounted for 60% of the total number of stars earned.

In this investigation, the 80/20 rule considers those in the top two categories to be the top 20% of students (as shown above).

By adding these two categories together, we calculated that the top 20% of students have earned 79.4% of all the stars unlocked in Doodle — a remarkable fit to the 80/20 rule!

Or discover Doodle for schools

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