8. Monitoring, Updates, and Review Timing
How the scores are refreshed, and what changes between versions.
The scores are recomputed on a recurring cycle from a refreshed copy of the providers' published price data, and each run writes one row for every combination of data version, provider, and region. No run partially updates a previous version, so a version is internally consistent and every region in it was scored against the same basket and the same band boundaries.
Two consequences follow for anyone tracking a region over time. The comparison basket is refitted each run, so a provider launching or retiring product categories changes the composition of the basket the region is scored on. The band boundaries are refitted each run as well, which means a region can move from one grade to the next without any change to its own prices, if the distribution around it has shifted. The two percentages are the stable output across versions, and Section 11 states the resulting interpretation rule.
Changes to a provider's published price list structure are found through the translation layer described in Section 5, since a change in field semantics normally presents as an unusual number of removed prices in the run that follows it.