Pareto Chart for Defect Analysis — Six Sigma QA & Manufacturing 80/20
A defect analysis Pareto chart ranks non-conformities by occurrence count and overlays cumulative percentage ($C_k = \sum_{i=1}^k d_{(i)} / D_{total}$) to guide DMAIC root-cause corrective action.
Tip: Paste Excel or Google Sheets rows (Ctrl+V / ⌘V) directly into any cell.
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Defect share: p_i = d_i / sum(d). Cumulative defect coverage at rank k: Cum_k = sum_{i=1..k}(p_(i)) * 100%. 80/20 Vital Few: {i : Cum_i <= 80%}.
Chart Design & Use-Case Tips
- 01Defect share: p_i = d_i / sum(d). Cumulative defect coverage at rank k: Cum_k = sum_{i=1..k}(p_(i)) * 100%. 80/20 Vital Few: {i : Cum_i <= 80%}.
- 02In Six Sigma DMAIC (Analyze phase), tackle the defect modes to the left of the 80% cumulative line first for maximum yield improvement per engineering hour.
- 03Re-run the Pareto chart after corrective actions to verify that both total height and the primary bar have dropped.
- 04Export as Vector SVG for inclusion in ISO 9001 or IATF 16949 quality audit reports.
Frequently Asked Questions
How is a Pareto chart used in Six Sigma DMAIC?+
During the Measure and Analyze phases, teams plot defect counts by category to prove statistically which 2 or 3 failure modes warrant a fishbone (Ishikawa) 5-Whys investigation.
Should I group rare defects into an 'Other' category?+
If you have more than 8–10 tail categories with 1 or 2 occurrences each, combining them into 'Other' keeps the x-axis crisp.
Does the chart re-sort automatically if a lower defect spikes?+
Yes, editing any count in the workbench immediately re-ranks the bars in descending order and recalculates the cumulative curve.