Guardrail metrics monitor qualities that must not deteriorate while improving a primary outcome. A conversion lift can coincide with more payment errors or refunds.
The demo shows a conversion bar passing its target while an error gauge crosses its limit, holding the decision. Define thresholds and observation windows before the test.
Too many metrics create noisy alarms. Pick a small set tied to customer harm, and handle severe incidents through operating procedures even before statistical completion.
When to use
Use it for checkout or signup changes where conversion alone is insufficient.