What does Pareto analysis show?
Method: Pareto analysis shows how a measured total is distributed across categories. It helps locate concentration, but the data decides the pattern rather than an assumed 80/20 rule.
Calculate concentration from measured values
- Use one consistent outcome measure.
- Clean overlapping or duplicated category names.
- Sort categories by measured contribution.
- Review severity and controllability before choosing action.
Read the cumulative share without forcing 80/20
If rework contributes 42 hours, waiting 28, missing information 18, and other causes 12, the first two categories account for 70% of measured delay. That concentration guides investigation without claiming a universal ratio.
Contribution is not the same as cause or priority
Keep category definitions stable
Categories that overlap can double-count the same event, while changing labels can split one mechanism across several rows. Review the raw records and write a short inclusion rule for each category before interpreting the cumulative curve.
Use the cumulative percentage to choose where deeper analysis begins. Then add severity, control, cost, and feasibility before selecting an intervention.
Boundary of the result
A large category is not automatically the easiest, safest, or most valuable category to change.
Continue with the method
Use the Pareto analysis article and the problem prioritization guide and the pre-mortem risk planner to move from a quick result to a complete reasoning process.