Day 59 of 60 · AI-system specific

RAG retrieval evaluation

Bad retrieval makes a good model hallucinate. Without precision, recall, and grounding metrics, RAG quality is folk wisdom dressed up as engineering.

ProblemRetrieval-augmented systems hallucinate when retrieval misses or returns garbage.

How it works

Measure retrieval precision, recall, MRR on a held-out set. Score generation against retrieved context (faithfulness, grounding).

What it catches

Retrieval misses, ungrounded generation, attribution drift. Without it, RAG quality is folk wisdom.

Tools

Ragas · OSS TruLens · OSS Phoenix · OSS

Verdict by project size

Small
Skip
Medium
Opt
Large
Rec
Extra-large
Must

Cost

Project size Setup Maint / mo Tool / mo CI / run
Small <10k LOC 1d 1h $0 +1m
Medium 10–100k LOC 3d 5h $0 +3m
Large 100k–1M LOC 15d 30h $500 +10m
Extra-large >1M LOC 50d 120h $5k +20m
Setup = engineer-days to first useful run · Maint = engineer-hours / month at steady state · Tool = out-of-pocket $ / month · CI = minutes added (or saved) per pipeline run

Lifecycle & ownership

When in lifecycle
Test Operate Observe
Per merge · Runs after merge to main; nightly heavy jobs.
Who owns it
ML / AI Engineer
Models, evals, drift, guardrails
Collaborates with: Developer, Security / AppSec

Reference implementations

Quick check

Without RAG retrieval evaluation, RAG quality becomes…

One question. Pick the best answer. Your streak is saved locally on this device.

Save the lesson

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thinkbridge THE VALIDATION ATLAS DAY 59 OF 60 AI-SYSTEM SPECIFIC RAG retrievalevaluation Bad retrieval makes a good model hallucinate. Withoutprecision, recall, and grounding metrics, RAG quality isfolk wisdom dressed up as engineering. FIVE-MINUTE LESSON · ONE QUICK-CHECK QUESTION There’s a new way there
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