Reference series
Price indexes
Each index tracks the median award value for one benchmark category against a fixed cohort, rebased so the first published period equals 100. Because the cohort is held constant, movement reflects what contracts cost rather than which contracts we happened to include.
Published indexes
Revision policy
An index value is never overwritten. When a period is recomputed and the answer changes, the new value is published as a new dated vintage and the previous one remains retrievable at the date it was published. A citation of a dated vintage therefore keeps meaning what it meant.
Every revision states its cause. late_reporting means more awards were reported for a period that had already been published. source_corrections means awards were corrected or deleted upstream, so the period has fewer records than before. recomputation means the sample did not change and the value did, which is the case we investigate rather than publish quietly.
A period is published only when its underlying benchmark snapshot met the minimum sample size and cleared the anomaly gates. Withheld periods are absent from the series rather than interpolated.