Range
Search usage and search volume.
KPI Framework
Measure search in layers, not with one final grade.
A good framework combines usage, quality, interaction and commercial outcomes.
Quality
Zero-result searches, relevance judgments and reformulations.
Interaction
CTR, Filter usage and suggestion selection.
Conversion
Attributed orders and value within the same store.
Operational
Latency, index freshness and event coverage.
Commercial
Revenue, margin and campaign impact where reliable measurable.