Sealed Baseline

A sealed baseline is what turns claims like 'we got better' or 'nothing material changed' from assertions an institution is asking to be trusted into claims a counterparty can independently check. It is captured at a defined point in time, model versions, inputs, and outputs, and stored in a form nobody, including the team that built the models, can quietly revise afterward; any correction has to happen as a new, dated entry rather than an edit to the old one. Sealed baselines serve three specific institutional uses. In backtesting, a sealed baseline is what makes 'frozen at cutoff' an operational fact rather than an unverifiable claim, since a reviewer can confirm the baseline's timestamp predates every matter in the scored population. In disclosure, a sealed baseline gives an institution a fixed prior state to describe a methodology or corpus change against, replacing a vague description of updates with an exact before-and-after comparison. In internal improvement programs, a sealed 'before' state lets an institution prove a strengthening initiative actually worked rather than relying on its own retrospective, and typically flattering, account of prior performance. Governance around sealed baselines should specify who can create one, on what cadence, and what triggers an unscheduled baseline outside that cadence, ideally with independent attestation at the moment of sealing rather than only when a dispute later requires it.