Mistake Fingerprint methodology

A Mistake Fingerprint is a decision-consistency indicator built from analyzed games. It is not Elo, a diagnosis, or a promise of rating improvement.

Publication threshold

A dimension receives a number only after at least five eligible decisions across at least three distinct games. Otherwise BlunderLoop shows “Not enough evidence.”

Formula

The starting score is 100 × (handled decisions + 0.5 × inconclusive decisions) ÷ eligible decisions. A severity penalty of up to 20 points reflects the average winning-chance loss. The result is clamped to 0–100 and rounded.

Confidence

• Low: 5–9 eligible decisions
• Medium: 10–19
• High: 20 or more

Privacy and limitations

Shared Fingerprints contain selected aggregate scores, denominator, confidence, a week-rounded date range, and an optional first name. They exclude PGN, FEN, moves, opponents, platform handles, email, private IDs, and Coach text. A pattern describes supported decisions in analyzed games—not your overall chess ability.