Synthetic portfolio study
Published study
RAG Reliability study
A proprietary product direction for deciding when a RAG system should answer or defer, supported here by a synthetic answer/defer study.
This page documents a completed synthetic portfolio study with pre-registered evaluation criteria. Technical summary and public metrics are available here; source code and full artifacts remain private. Results apply only to the fixed benchmark described below.
Context
RAG Reliability is a proprietary product direction for deciding when a RAG system should answer or defer. Study v1 uses a synthetic Atlas Support Operations corpus with a frozen holdout so that evaluation, failure analysis and artifact integrity remain reviewable. Public results are summarised on this page; implementation details and full artifacts remain private. A controlled public demonstration of the Explorer is linked from this page.
Problem
High retrieval relevance alone does not guarantee that a system should answer. The evaluated pipeline must also handle conflicting lexical and dense rank-1 results, obsolete versus current documents, answerable queries, queries that require clarification, queries where abstention is appropriate, and the precision-coverage trade-off introduced by deferral.
Scope
- Lexical BM25 baseline.
- Dense MiniLM baseline.
- Equal-weight hybrid reciprocal-rank fusion.
- Status-aware current-first reranking.
- Retrieval-consensus analysis.
- Selective-risk analysis.
- Signal-separability analysis.
- Versioned v2 synthetic benchmark.
- Frozen development/holdout split.
- Top-1 gate pre-registration.
- One-time holdout evaluation.
- Deterministic artifact registry and SHA-256 evidence package.
Constraints
- Synthetic benchmark only; no production traffic or real enterprise corpus.
- 36-query holdout with fixed query composition.
- Gate rules and success criteria were frozen before holdout evaluation.
- Development and holdout were separated until the one-time evaluation.
- Holdout status: unblinded. The holdout cannot be reused as unseen evidence.
- Post-holdout gate tuning on this benchmark is prohibited.
- Integrity regeneration is a reproducibility check only.
- Results cannot support population-level or production deployment claims.
- Source code, tests and full study artifacts are not publicly distributed.
Evaluation pipeline
- 01
Lexical retrieval
BM25 provides exact-term and token-overlap evidence.
- 02
Dense retrieval
Pinned MiniLM embeddings provide semantic retrieval evidence.
- 03
Hybrid fusion
Reciprocal-rank fusion combines lexical and dense rankings with equal weights.
- 04
Status-aware reranking
Current documents are prioritised over obsolete evidence.
- 05
Top-1 consensus gate
Answer only when BM25, dense and final current evidence share the same rank-1 document; otherwise defer.
Approach
- 01
Establish baselines
Define lexical BM25 and dense MiniLM retrieval baselines on the synthetic corpora.
- 02
Evaluate hybrid retrieval
Combine lexical and dense rankings with equal-weight reciprocal-rank fusion and apply status-aware current-first reranking.
- 03
Analyse gate failures
Examine consensus-gate failures and signal separability to understand when retrieval evidence supports an answer decision.
- 04
Create frozen benchmark
Build the versioned v2 synthetic benchmark with a fixed development/holdout split.
- 05
Pre-register gate and criteria
Freeze the top-1 consensus gate rules and three success criteria before any holdout access.
- 06
Run holdout evaluation
Execute the one-time unblinded holdout evaluation without changing the gate or thresholds.
- 07
Consolidate evidence package
Assemble deterministic JSON reports, a 33-artifact integrity registry and a versioned study package.
Deliverables
- Versioned synthetic corpora.
- Typed retrieval and evaluation implementation.
- Deterministic JSON reports.
- Pre-registration artifact.
- One-time holdout report.
- Final study report.
- 33-artifact integrity registry.
- Automated integrity and reproducibility checks.
- Versioned study package with SHA-256 verification.
Technologies
- Python
- uv
- pytest
- BM25
- sentence-transformers
- all-MiniLM-L6-v2
- reciprocal-rank fusion
- SHA-256 artifact verification
Evidence
Pre-registered synthetic holdout result
Frozen success criteria
PASS 3/3
All three criteria were frozen before holdout evaluation and passed without changing the gate or thresholds.
Synthetic holdout metric
Answered-query precision
17/20 = 0.850
Required value was at least 0.75.
Synthetic holdout metric
Answerable-query coverage
17/22 = 0.773
Required value was at least 0.70.
Synthetic holdout metric
False-answer rate
3/14 = 0.214
Required value was at most 0.50 for queries expected to defer.
Descriptive synthetic holdout metric
Decision accuracy
28/36 = 0.778
Accuracy was reported alongside precision, coverage and deferral errors; it was not a frozen success criterion.
Reproducibility evidence
Evidence package
33 registered artifacts across 12 stages
The study is based on a reproducible internal benchmark over a synthetic support corpus. Public results are summarised here; source code and full artifacts remain private.
Limitations
- Single synthetic benchmark with a small fixed 36-query holdout.
- Fixed answer, clarify and abstain query balance.
- No evidence about real support workloads or enterprise corpora.
- No calibrated probability or confidence score is produced.
- No generative-answer evaluation was performed.
- Three false answers occurred on abstain queries.
- Five answerable queries were deferred.
- No generalisation evidence for other corpora, domains or languages.
- The holdout is unblinded and cannot be reused as unseen evidence.
- The study does not claim production validation or guaranteed answer correctness.
Production considerations
- Independently designed real-corpus holdout with representative traffic and prevalence estimates.
- Document lifecycle and status governance.
- Retrieval and deferral monitoring with latency and cost measurement.
- Access control and sensitive-data handling.
- Human escalation paths for deferred or low-confidence queries.
- Answer-generation evaluation beyond retrieval consensus.
- Incident review and rollback procedures.
- New confirmatory data for any modified gate before deployment.
Service relevance
- RAG Reliability Audit of existing systems.
- Answerability and abstention policy design.
- False-answer and evidence-conflict analysis.
- Synthetic and representative evaluation design.
- Status-aware knowledge retrieval.
- Evaluation protocol design.
- Technical evidence and decision reporting.