Root Cause Analyzer Calculator

Analyzer Inputs

Score suspected causes, then focus on the vital few.

Problem statement

Keep it factual: what, where, when, how many.

Process / line

Incident date

Team / shift

Lot / batch

Method

Uses risk scoring plus 80/20 focus.

Notes / containment

Cause scoring table

Scores use 1–10 for O/S/D, and 0–100 for evidence.

Detection: 1 = easy, 10 = hard

Cause	Category	O	S	D	Evidence %	Impact cost	Owner	Corrective action	Remove
					0–100 strength	Optional
					0–100 strength	Optional
					0–100 strength	Optional

Weighting controls

Tune how strongly each factor drives ranking.

Severity weight

Occurrence weight

Detection weight

Evidence weight

Cost weight

Set to 0 to ignore cost.

Optional: 5 Whys trail

Write your chain of “why” to confirm the mechanism.

Why 1

Why 2

Why 3

Why 4

Why 5

Tip: Use evidence to avoid “loud” opinions. Score only what you can defend.

Example data table

These sample values show how ranking and Pareto focus work.

Cause	Category	O	S	D	Evidence	Impact
Worn guide rail scratches surface	Machine	7	6	8	80%	1500
Packaging foam density out of spec	Material	5	7	6	60%	900
Inspection sampling too small	Measurement	4	5	9	55%	0
Operator handling varies by shift	Man	6	4	6	50%	250

Use the “Load sample” button to auto-fill similar rows.

Formula used

1) Base risk score

Base = Severity^wS × Occurrence^wO × Detection^wD

Severity: impact size (1–10).
Occurrence: how often it happens (1–10).
Detection: how hard to catch (1–10).

2) Evidence + cost adjustment

Weighted = Base × EvidenceFactor × CostFactor

EvidenceFactor scales with evidence strength.
CostFactor uses a log scale for stability.
Set cost weight to zero to ignore cost.

3) Pareto focus

Share% = Score ÷ TotalScore × 100. Causes that keep cumulative share near 80% are flagged as “Key”.

How to use this calculator

Write a clear, measurable problem statement.
List suspected causes, one per row.
Score O/S/D using consistent team criteria.
Enter evidence strength for each cause.
Optionally add impact cost and an owner.
Adjust weights only if your policy requires it.
Analyze, then tackle the Pareto key causes first.

FAQs

1) What does detection score mean here?

Detection is “difficulty to detect.” A higher number means the issue is more likely to escape checks, raising the overall risk score.

2) Why include evidence strength?

Evidence helps separate plausible causes from guesses. Stronger evidence increases confidence and pushes a cause higher in the prioritized list.

3) Should we always use cost weighting?

Not always. Use cost weighting when financial impact is required. Keep it at zero when you want pure risk ranking.

4) How many causes should I list?

Start broad, then refine. Ten to twenty causes is common. Remove duplicates and rewrite vague items into specific mechanisms.

5) What if the Pareto key set is too large?

Improve cause definition and evidence quality. Merge overlapping causes, then rescore. A sharper list usually makes the key set smaller.

6) Is this a replacement for a fishbone diagram?

No. Use a fishbone to brainstorm and structure causes. Then use this tool to quantify, rank, and decide what to test or fix first.

7) How do I validate the top-ranked cause?

Run a controlled check: isolate the suspected factor, compare before/after data, and confirm defect reduction. Then lock the corrective action in standard work.