Comparison
Online Evaluation vs Regression Testing (LLMs)
Online Evaluation and Regression Testing (LLMs) are both common AI/LLM terms but cover different ideas. Here is a quick side-by-side.
When you would reach for Online Evaluation
After offline eval is solid and you have meaningful production volume. Stretch your eval coverage from a fixed set to a live one.
Phoenix running a faithfulness eval on 5% of production RAG traces, dashboard charts the rolling 7-day mean.
When you would reach for Regression Testing (LLMs)
As soon as you have repeat bugs or "we fixed that already, didn't we?" moments.
A PR template requires: zero regressions on the 30 must-pass examples; overall win rate ≥ 50%; cost per call within 10% of baseline.
Frequently asked
What is the difference between Online Evaluation and Regression Testing (LLMs)?
Online Evaluation: Online evaluation runs scoring functions over live production traffic — usually a sample of recent traces — to monitor quality continuously instead of relying solely on a fixed offline dataset. Regression Testing (LLMs): LLM regression testing is the practice of running every prompt or model change against a fixed set of "must-pass" examples — bug repros, edge cases, known failure modes — to catch quality regressions.
When should I use Online Evaluation vs Regression Testing (LLMs)?
After offline eval is solid and you have meaningful production volume. Stretch your eval coverage from a fixed set to a live one. As soon as you have repeat bugs or "we fixed that already, didn't we?" moments.
Are Online Evaluation and Regression Testing (LLMs) the same thing?
No. Online Evaluation is evaluation; Regression Testing (LLMs) is evaluation. They are related but address different parts of the AI stack.