Module 3 · Lesson 7 of 17
Pareto analysis
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Learning objectives
- Construct a Pareto chart with valid categories.
- Choose count, cost or time as the ranking measure.
- Interpret a Pareto without over-claiming causation.
Focus, not proof
A Pareto ranks categories descending and adds cumulative share. It focuses attention on the categories that dominate frequency or impact.
The tallest bar is not the root cause; it is where investigation should start after the categories themselves are validated.
Garment-factory example
A defect Pareto shows ‘skipped stitches’ dominates count while ‘shade rejection’ dominates cost; both views produce different priority lists and both are legitimate.
Method
- Confirm categories are mutually exclusive and exhaustive.
- Choose count, cost or time as the ranking measure.
- Sort descending and add cumulative percentage.
- Stratify when aggregation hides an obvious subgroup.
Common mistakes
- Comparing percentages without exposure.
- Treating the tallest bar as the confirmed root cause.
Knowledge check
Pick one answer per question. Explanations appear after you submit.
1. A Pareto chart primarily helps to:
2. Count and cost Paretos may disagree because:
Author: NOSK.life · Last reviewed: 2026-07-21