Pareto Principle (80/20 Rule)

The Pareto Principle, named after economist Vilfredo Pareto, states that roughly 80% of effects come from 20% of causes. Pareto originally observed that 80% of Italy's land was owned by 20% of the population. The pattern shows up everywhere: 80% of revenue comes from 20% of customers, 80% of bugs come from 20% of the code, 80% of results come from 20% of efforts.

1. Identify the area to analyze — What results do you want to improve? Revenue, productivity, bug reduction, customer satisfaction?
2. List all contributing factors — What inputs, activities, or causes produce those results?
3. Measure the impact of each — Quantify how much each factor contributes to the overall result.
4. Rank by impact — Sort from highest to lowest contribution.
5. Identify the vital few — Find the ~20% of inputs that produce ~80% of the output.
6. Focus and act:

• Double down on the vital few — invest more time, money, and energy here
• Reduce or eliminate the trivial many — stop doing low-impact activities
• Automate or delegate anything that must continue but isn't in the vital few

• Features: 20% of features are used by 80% of users → Focus development on those features
• Bugs: 20% of modules contain 80% of bugs → Prioritize refactoring those modules
• Customers: 20% of customers generate 80% of support tickets → Create targeted resources for their common issues
• Sales: 20% of marketing channels bring 80% of leads → Increase investment in those channels
• Time: 20% of your daily activities produce 80% of your meaningful output → Protect and expand that time

The Pareto Principle helps you focus your limited resources on what actually matters. By identifying the vital few, you can achieve dramatically more with the same or less effort.