ND Quality Metrics — Intuitive Guide

Rank instability

• Question it answers: “Would the order change if I reran this?”
• Good value: close to zero.
• If bad: enable witness mode or raise recall.

Distance margin

• Question it answers: “How separated are the top results?”
• Good value: larger margins feel safer.
• If bad: lower k or switch to exact for verification.

Similarity entropy

• Question it answers: “Are the results all basically the same?”
• Good value: moderate entropy (not uniform noise).
• If bad: tune parameters or review the corpus quality.