1. Objective
Measure retrieval completeness, chunk boundary preservation, and citation faithfulness in compliance Q&A pipelines when queries depend on date-bound exceptions located in disparate policy appendixes.
2. Dataset
1,200 synthetic and open-source corporate governance policy documents comprising 4,500 ground-truth query-answer pairs. Each test pair incorporates cross-document dependencies where a baseline policy clause is amended or exempted in a secondary section.
3. Method
Dual-pass deterministic testing comparing two retrieval pipelines against a frozen instruction model: (A) Dense vector similarity search with a standard 512-token chunking window; (B) Hybrid retrieval (dense embeddings + BM25 keyword matching) paired with a cross-encoder re-ranking model scoring top-25 chunks down to top-5.
4. Metrics
We evaluate four automated metrics verified against human annotator rubrics: Context Recall @ k (percentage of required evidence chunks retrieved), Context Precision @ k (signal-to-noise ratio in prompt context), Faithfulness Groundedness (verifiable alignment between output claims and retrieved context), and Answer Relevance.
5. Results (Sample Telemetry)
| Evaluation Metric | Pipeline A (Dense 512) | Pipeline B (Hybrid + Re-rank) | Delta |
|---|---|---|---|
| Context Recall (amendment clauses) | 74.2% | 93.1% | +18.9% |
| Context Precision (top-5 chunks) | 88.0% | 94.6% | +6.6% |
| Faithfulness (date disambiguation) | 81.5% | 91.8% | +10.3% |
6. Failure Analysis
Root cause analysis revealed that in 82% of pipeline A errors, the correct amendment chunk was retrieved at rank 7 or 8, falling outside the top-5 generator context window. The generator was not hallucinating; the retrieval step had omitted the critical exception evidence. Introducing the cross-encoder re-ranking stage promoted these amendment clauses into the top-3 positions.
7. Limitations
This evaluation suite focused on text-based regulatory documents. Scenarios involving dense tabular appendices or embedded flowchart diagrams require separate multimodal OCR evaluation harnesses.