Movement Log

A movement log is an append-only record of how a quantity has changed over time. Each entry is timestamped, sourced, and never edited. The log is the primary credibility artifact for claims that move — race ratings, economic indicators, polling averages, anything where the value today is not the value last week.

For race ratings specifically, Thin Gold ships a public Movement Log (forthcoming in Sprint 2) that lists every rating change since 2026-01-01: the date, the race, the from-rating, the to-rating, and a one- or two-paragraph reasoning paragraph. The point is to make the publication’s track record auditable. Readers can verify that a race we now rate Toss-up was Lean R two months ago, see why we moved it, and decide whether they trust our judgment going forward.

The movement log is more useful than a forecast model for non-statistical readers. A model that says “57.3% chance of D win” is harder to interpret than “we moved this from Lean R to Toss-up on April 14 because Brown’s Q1 raise doubled Moreno’s.”