CAPA Root Cause Analysis Methods 3 — Questions and Answers
Question 1: What distinguishes a 'contributing cause' from a 'root cause' in RCA?
- A contributing cause is documented while a root cause is not
- A contributing cause increases the likelihood of the problem but alone would not produce it (Correct answer)
- A contributing cause is always human error
- A contributing cause occurs after the problem appears
Correct answer: A contributing cause increases the likelihood of the problem but alone would not produce it
A contributing cause is a factor that influences the problem's occurrence but is not sufficient on its own to produce it, unlike the root cause.
Question 2: In Failure Mode and Effects Analysis (FMEA), the Risk Priority Number (RPN) is calculated as:
- Severity + Occurrence + Detection
- Severity × Occurrence × Detection (Correct answer)
- Severity × Occurrence / Detection
- Occurrence / (Severity × Detection)
Correct answer: Severity × Occurrence × Detection
RPN is the product of Severity, Occurrence, and Detection ratings, each scored on a 1–10 scale, to prioritize failure modes for corrective action.
Question 3: An affinity diagram is most useful in the RCA process when:
- Calculating statistical process control limits
- Organizing large volumes of qualitative ideas or data into logical groupings (Correct answer)
- Plotting defect frequency over time
- Verifying that a corrective action eliminated the root cause
Correct answer: Organizing large volumes of qualitative ideas or data into logical groupings
Affinity diagrams help teams organize brainstormed ideas or data points into natural groupings to reveal underlying themes or root cause categories.
Question 4: Which statement best describes the 'Is / Is Not' method used in RCA?
- It maps all possible failure modes in a system
- It defines what the problem is and is not to narrow the search for root causes (Correct answer)
- It calculates the probability of each cause
- It ranks causes by cost impact
Correct answer: It defines what the problem is and is not to narrow the search for root causes
The Is/Is Not method systematically defines the boundaries of a problem by specifying where, when, and to what extent the problem does and does not occur.
Question 5: In process failure analysis, a 'latent cause' refers to:
- A cause visible on the production floor
- An underlying systemic weakness that enables failures to occur and remain undetected (Correct answer)
- The last event before the failure
- A cause identified only after a recall
Correct answer: An underlying systemic weakness that enables failures to occur and remain undetected
A latent cause is a dormant systemic flaw — such as inadequate procedures or oversight gaps — that sets the stage for active failures.
Question 6: When should a team switch from a simple 5 Whys analysis to a more complex method like FTA?
- When the problem involves a single process step
- When multiple interacting causes create a complex failure scenario (Correct answer)
- When the defect rate is below 1%
- When corrective actions have already been implemented
Correct answer: When multiple interacting causes create a complex failure scenario
FTA is preferable when failures arise from multiple interacting causes or when a single linear chain of whys is insufficient to model the problem.
Question 7: Which of the following actions validates that an RCA has correctly identified the root cause?
- Management approval of the corrective action plan
- Temporary containment eliminates the defect
- Removal of the identified root cause prevents recurrence (Correct answer)
- The team reaches consensus on the cause
Correct answer: Removal of the identified root cause prevents recurrence
True validation occurs when eliminating the identified root cause demonstrably prevents the problem from recurring, proving the diagnosis was correct.
CAPA Root Cause Analysis Methods 3
What distinguishes a 'contributing cause' from a 'root cause' in RCA?