Investigation Input Panel
Enter one suspected cause at a time and compare exported results later.
Example Data Table
| Suspected Cause | Category | Defect Type | Defects | Units | Occurrence | Severity | Detectability | Recurrence | Downtime | Cost | Root Index |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Worn sealing jaw | Machine | Seal leak | 18 | 600 | 8 | 9 | 7 | 8 | 9.5 h | 2400 | 76.8 |
| Moisture in resin | Material | Surface blister | 11 | 900 | 6 | 7 | 8 | 6 | 4.0 h | 1350 | 60.1 |
| Unclear setup sheet | Method | Torque variation | 9 | 500 | 7 | 8 | 5 | 7 | 3.2 h | 980 | 58.3 |
Formula Used
Defect Rate (%) = (Defect Count / Inspected Units) × 100
Traditional RPN = Occurrence × Severity × Detectability
Scaled Impact Scores convert downtime, cost, containment time, and escapes into 1–10 ranges.
Root Index = 10 × [(0.16×Occurrence) + (0.16×Severity) + (0.14×Detectability) + (0.14×Recurrence) + (0.10×Process Spread) + (0.08×Downtime Score) + (0.08×Cost Score) + (0.05×Containment Score) + (0.05×Escape Score) + (0.04×Evidence Strength)]
Action Priority = Root Index × (1 + Defect Rate / 100)
Confidence (%) = min[100, (Evidence×6) + (Recurrence×4) + (Spread×3) + (Escape Score×2)]
How to Use This Calculator
- Enter the suspected cause, category, and defect type.
- Input defect quantity, inspected units, and customer escapes.
- Score occurrence, severity, detectability, recurrence, spread, and evidence on a 1 to 10 scale.
- Add downtime, rework cost, and containment hours for operational impact.
- Press Find Root Priority to show the result above the form.
- Use CSV or PDF export to save findings for reviews.
- Repeat for other suspected causes and compare the outputs.
Interpretation Notes
Higher root index values suggest stronger investigation priority. The score does not prove the cause. It helps rank where teams should focus validation first.
Combine the result with fishbone analysis, 5 Whys, process walk observations, maintenance history, and verification tests before closing corrective actions.
Frequently Asked Questions
What does this calculator actually estimate?
It estimates a weighted root cause priority using defect frequency, severity, detectability, recurrence, cost, downtime, escapes, and evidence strength.
Is the result a replacement for formal RCA methods?
No. It supports investigation focus. You should still confirm causes using 5 Whys, fishbone analysis, containment checks, and process evidence.
Why is detectability included in the score?
Hard-to-detect causes create more escapes and hidden risk. A higher detectability score raises the root priority for investigation and controls.
How should I score evidence strength?
Use higher values when you have repeatable data, direct observations, tests, or traceable records linking the suspected cause to the defect.
Can I compare several suspected causes?
Yes. Run each suspected cause separately, export the results, and rank them by root index, urgency, and confidence.
What does process spread mean here?
Process spread measures how widely the issue appears across lines, batches, shifts, stations, or products. Wider spread increases investigation priority.
When is a score considered critical?
A root index of 80 or above is treated as critical. These cases deserve fast containment, leadership review, and deeper verification.