Case study
Independent Quality Assurance of a Document-Based RAG Chatbot
The Challenge
A document-based RAG chatbot enabled users to upload documents and ask questions, generating contextual responses with supporting references.
QASource conducted an independent AI assurance assessment to evaluate retrieval accuracy, response reliability, citation correctness, handling of unanswerable queries, and protection of sensitive information.
Assessment Scope
The assessment covered:
- Retrieval Quality: Relevance and completeness of retrieved information.
- Response Quality: Factual correctness, completeness, groundedness, and faithfulness.
- Citation Accuracy: Whether references supported generated claims.
- Unanswerable Queries: Appropriate handling of missing information without unsupported responses.
- Privacy and PII Protection: Prevention of sensitive information exposure and unauthorized access.
Evaluation Methodology
A structured dataset of test scenarios was used, covering factual, multi-part, multi-document, context-dependent, and unanswerable queries, including sensitive information scenarios.
Testing included:
- Retrieval relevance and context coverage.
- Response accuracy, completeness, and hallucination checks.
- Citation and source validation.
- Abstention behavior for unanswerable queries.
- Failure analysis using source documents, retrieved context, and generated responses.
Each finding was documented with expected and actual behavior, supporting evidence, severity, and potential impact.
Privacy and Access-Control Assessment
A dedicated set of privacy-focused scenarios evaluated PII handling and access controls, including direct information requests, unauthorized disclosure attempts, cross-document retrieval, and prompt-based access-control bypass.
Corrective Actions and Verified Improvements
Recommendations focused on improving retrieval relevance, response grounding, citation validation, multi-part answer completeness, and privacy controls.
Following the implementation of corrective actions over a couple of sprint cycles, final testing results demonstrated the following improvements:
| Evaluation Area | Initial | Post-Fix |
|---|---|---|
| Retrieval Accuracy | 88% | 94% |
| Correctness | 84% | 95% |
| Completeness | 75% | 93% |
| Citation Correctness | 79% | 97% |
| Hallucination Rate (Lower Is Better) | 18% | 5% |
| Abstention Accuracy | 78% | 96% |
| PII Leakage Rate (Lower Is Better) | 12% | No PII disclosure was observed across the post-remediation privacy scenarios |
| Calculation Accuracy | 92% | 100% |
| Consistency | 83% | 90% |
Previously failing scenarios were individually retested, with unresolved issues documented for further investigation.
Outcome: Evidence-Based Confidence in AI Reliability
QASource provided an independent assessment of the chatbot's retrieval effectiveness, response reliability, citation accuracy, and privacy risks.
The engagement established a repeatable assurance approach combining structured evaluation datasets, evidence-based findings, regression testing, and post-fix verification to support continued improvements in AI reliability, information integrity, and privacy.