Gauge
Relevance, measured and explained
How relevant is this item to this need? That should be something you can quantify, compare, and ask “why?” about. Gauge is about measuring relevance with explicit rules and giving explanations you can inspect.
The question it cares about
Rankings made by gut feel are hard to check; after a rule changes, you can't tell whether things got better or worse.
Where it sits in the family
The one that reads the level. It stands on its own, alongside Inlet and Sluice.