Analyzer Inputs
Example Data Table
| Inspection Lot | Units Inspected | Scratch | Mislabel | Leak | Critical | Major | Minor |
|---|---|---|---|---|---|---|---|
| Lot A | 500 | 6 | 3 | 2 | 1 | 4 | 6 |
| Lot B | 400 | 4 | 2 | 1 | 0 | 3 | 4 |
| Lot C | 600 | 9 | 4 | 1 | 1 | 5 | 8 |
| Lot D | 300 | 3 | 1 | 0 | 0 | 2 | 2 |
| Lot E | 700 | 10 | 6 | 2 | 2 | 6 | 12 |
Formula Used
- Total Defects = Σ(category counts) (or severity total if categories are empty).
- DPU = Total Defects ÷ Units Inspected.
- Total Opportunities = Units Inspected × Opportunities per Unit.
- DPO = Total Defects ÷ Total Opportunities (requires opportunities).
- DPMO = DPO × 1,000,000.
- Yield (simple) = 1 − DPU (clamped 0–1).
- Yield (Poisson) = e^(−DPU) (recommended for multiple defects per unit).
- Sigma ≈ NORMSINV(1 − DPMO/1,000,000) + shift (optional shift = 1.5).
- Severity Score = wC×Critical + wM×Major + wN×Minor.
- COPQ = Total Defects × Cost per Defect.
- Escaped Defects = Total Defects × (1 − Detection%).
How to Use This Calculator
- Enter your inspected units and optional opportunities per unit.
- Fill issue categories with counts for a Pareto breakdown.
- Add severity counts and adjust weights to reflect risk.
- Set detection effectiveness and cost per defect for impact.
- Click Analyze to view results above the form.
- Download CSV or PDF for audits, reviews, and reporting.
Defining the defect baseline
Start with the inspection scope and a clear defect definition. Units inspected form the denominator for Defects per Unit, showing how frequently issues appear. When you enter opportunities per unit, the analyzer converts defects into Defects per Opportunity and DPMO, enabling comparison across products with different complexity. Keep counting rules consistent, especially whether multiple defects on one unit are recorded separately. Document counting rules always to keep teams aligned.
Reading Pareto contribution curves
Category counts drive a Pareto view that highlights the few causes behind most impact. The tool sorts categories, calculates percent share, and adds cumulative contribution to show where attention pays back. A practical target is reducing the top contributors until cumulative percent falls below about eighty percent. Confirm the top category with samples and traceability so the pattern is real. Recheck the top issue after fixes monthly.
Linking risk through severity weighting
Severity is not the same as frequency, so the analyzer separates both. Critical, major, and minor counts can be weighted to match risk, safety exposure, or customer impact. The weighted severity score and the severity rate per one thousand units help compare lots, suppliers, or shifts even when volumes differ. Review weights periodically with engineering and service, then keep them stable for trend reporting. Align weights with FMEA and customer needs.
Estimating capability, yield, and escapes
Yield estimates translate defect intensity into an outcome. Simple yield uses one minus DPU, while Poisson yield uses an exponential model and fits cases with multiple defects per unit. Capability is approximated from DPMO using an inverse normal transform, with an optional long‑term shift used in some reporting. Detection effectiveness estimates escaped defects and escape DPMO, guiding prevention and inspection improvements. Track escaped defects to strengthen containment decisions.
Turning metrics into actions
Metrics matter only when they drive decisions. Convert reduction opportunities into financial impact by multiplying defects by cost per defect to estimate cost of poor quality. Combine the top Pareto issue, severity weighting, and escape risk to prioritize corrective actions. After countermeasures, rerun weekly, track DPMO and escapes, and confirm gains with audits and control reviews. Review results weekly and update actions.
FAQs
What does DPMO represent in this analyzer?
DPMO estimates defects per one million opportunities, letting you compare processes with different complexity. Enter realistic opportunities per unit based on critical-to-quality checks, and keep that definition stable across reporting periods.
When should I use Poisson yield instead of simple yield?
Use Poisson yield when a single unit can contain multiple independent defects. It models defect occurrence intensity and avoids negative yield values that can appear when DPU exceeds one.
Why might category totals differ from severity totals?
Categories often reflect defect types, while severity counts reflect impact levels. If you enter both, align them by using the same defect log so frequency and severity describe the same underlying events.
How do I choose severity weights for critical, major, and minor?
Pick weights that reflect business risk, safety exposure, and customer consequences. Many teams start with 5–3–1, then adjust using complaint costs, FMEA rankings, and contractual requirements.
How should I interpret the sigma level output?
Sigma is a capability-style approximation derived from DPMO using an inverse normal transform. It is most useful for tracking trend direction. Only apply the optional long-term shift if your organization reports capability that way.
What are escaped defects and how can I reduce them?
Escaped defects are the expected share that bypasses detection, based on your entered effectiveness. Reduce escapes by improving prevention at the source, strengthening inspections at high-risk steps, and closing feedback loops from customer returns.