Implementation evidence
Procedure issued, tooling installed, software released, training completed, drawing changed or purchase requirement updated. Necessary, but normally insufficient alone to prove effectiveness.
Special Processes Institute
sp-i.org
Corrective Action Effectiveness Verification Report
Corrective Action Effectiveness Verification (CAEV)
A practical decision model for establishing whether a permanent corrective action has actually broken the causal chain and can credibly support corrective-action closure or an 8D D6 close-out. The app separates implementation evidence from effectiveness evidence, selects verification methods proportionate to risk, challenges the action through walk-throughs, talk-throughs and thought experiments, records physical and objective evidence, checks sustained performance, and produces an auditable verification report.
Effectiveness ≠ completion Challenge the causal chain Evidence must match risk No evidence · no closure
Not assessed
CA effectiveness verdict
0%
Evidence confidence
—
Verification risk level
0
Verification methods
0
Closure blockers
0%
Record completeness
What CAEV must prove
The question is not “Was the action completed?” The question is: “Does credible evidence demonstrate that the permanent corrective action has removed, controlled or sufficiently reduced the verified cause so that the original failure mechanism is prevented from recurring?” For an 8D D6 close-out, the implementation should be complete and the outcome should be validated with evidence appropriate to the problem and risk.
LinkProblem → verified cause
ExplainHow the CA breaks the chain
DefineSuccess before judgement
ChallengeTry to make it fail
MeasureCollect objective evidence
SustainConfirm performance over time
Effectiveness evidence
Challenge test passed, process or product result demonstrated, causal parameter controlled, recurrence absent across meaningful exposure, or comparable evidence showing the unwanted effect is prevented.
Counterfactual test
Reconstruct the original event and ask: if this corrective action had existed then, would it have prevented the event? If not, the action may not address the verified cause.
Try to make it fail
Deliberately introduce the initiating error where safe and practical. A robust control should detect, prevent or contain the error before the original unwanted effect occurs.
Sustainment matters
Immediate success can show capability. Sustained evidence shows the correction continues to operate under representative production, shifts, people, equipment, suppliers or conditions.
Independent judgement
For significant problems, effectiveness should not rely only on the person who implemented the action. Independent review increases confidence and reduces confirmation bias.
Verification method library
Combine methods for stronger evidenceWalk-through
Observe the real process from start to finish and ask where the new control prevents the original causal mechanism.
Talk-through
Give personnel a realistic scenario and ask them to explain exactly what they would do without leading them to the expected answer.
Thought experiment
Use a hypothetical but realistic condition to test whether the corrected system logically prevents recurrence, especially for rare events.
Counterfactual reconstruction
Replay the original event with the new control inserted. Identify the exact point at which the causal chain should now be broken.
Challenge / fault insertion
Where safe, deliberately introduce the original initiating error or an equivalent error and confirm that the control detects or prevents it.
Physical / functional test
Test the product, process, assembly or system under representative conditions and compare results with predefined acceptance criteria.
Process data / SPC
Verify the causal process characteristic is controlled through parameter records, capability, trend data, alarms or other objective measures.
Before / after comparison
Compare defect rate, escape rate, process result or other relevant metric before and after implementation with meaningful exposure.
Subsequent work sampling
Sample representative work after implementation across relevant lots, shifts, operators, machines, products, suppliers or dates.
Record / document audit
Verify changed requirements are deployed and records show the new control is used. Strong for implementation; usually pair with outcome evidence.
Personnel interview
Confirm the people performing the work understand the change, its purpose, abnormal-condition response and escalation route.
Customer / downstream confirmation
Where relevant, use customer, test, field or downstream process evidence to confirm the original unwanted effect is no longer present.
Evidence strength guide
| Level | Typical evidence | Interpretation |
|---|---|---|
| 1 · Administrative | Procedure revised, training record, action marked complete | Shows implementation; weak proof of effectiveness on its own. |
| 2 · Demonstrative | Talk-through, interview, controlled walk-through | Shows understanding and plausible operation; useful for low/medium risk or as supporting evidence. |
| 3 · Objective | Observed process, sampled records, measured output, before/after data | Direct evidence that the corrected process is operating and producing the intended result. |
| 4 · Challenged | Fault insertion, counterfactual replay, representative functional/environmental test | Strong evidence because the correction is deliberately tested against the failure mechanism. |
| 5 · Sustained / systemic | Meaningful exposure over time, multiple lots/shifts, systemic deployment, downstream confirmation | Highest confidence that the correction remains effective and is not a one-off success. |
Risk-based expectation
Higher risk requires stronger evidence.
Low risk may be adequately supported by implementation plus a walk/talk-through. Medium risk should normally include objective evidence. High or critical risk should normally include direct challenge/physical evidence and sustained verification unless a documented technical justification explains why this is not practicable.
Low risk may be adequately supported by implementation plus a walk/talk-through. Medium risk should normally include objective evidence. High or critical risk should normally include direct challenge/physical evidence and sustained verification unless a documented technical justification explains why this is not practicable.
Guided CAEV Record
1. Case & Problem0% complete
CAEV Decision
Complete the guided record and select Assess Effectiveness.
Closure Challenge
Final challenge: imagine the original circumstances occur again tomorrow. Walk or talk through the process. At exactly what point does the permanent corrective action stop the causal chain, and what evidence proves it?
CAEV / 8D D6 Close-out Report
Objective evidence and decision record. Organisational/customer requirements remain controlling.
Complete the guided CAEV record and assess effectiveness to generate the report.