reconstruction-is-diagnostic

Date: 2026-09-10. Status: superseded.

Decision. Reconstructing the PHS population-weighted bands from ranks and population is a diagnostic that never blocks a build and never replaces a published value.

Reason. The ingestion guarantee is source fidelity, not reproduction of the publisher's method.

Evidence. The midpoint rule reproduces every Scotland-level decile and quintile in all six editions; three 15% flag cells and two Shetland sub-geography zones differ. Expected exceptions are pinned in acceptance_baselines.yaml.