المدربA restatement is a later published change to a value already released: a company restating an earlier quarter’s accounts, a statistical agency revising a figure. A data vintage is the whole history of a series as it was published at one knowledge time. Backfill bias arises when history is added to a database after the fact, typically when a fund or a vendor’s new coverage enters with its past returns: the entrants chose to enter because their past was good, and the backfilled history was never available in real time.
