spb/wp22_uqo

1\section{Economic implications and applications}\label{sec:implications}23Three uses follow from a monthly municipal panel with reliability accounting. First, assessment: Quebec's triennial rolls are indexed to a reference date, and the ratio of sale prices to assessed values drifts between rolls; a municipal index with an interval gives assessors and the provincial agency a defensible time-adjustment factor for sales comparison, and the grade tells them when the factor should be the MRC's or the region's rather than the municipality's. Second, monitoring: the dispersion documented in Section~\ref{sec:empirical} means that provincial aggregates hide most of the variation that matters for local housing policy; the panel makes the variation visible while labelling the cells where it is not identified. Third, research: a constant-quality index at the municipal level with a measured revision profile is the input that studies of local demand shocks, migration, short-term rentals or zoning changes need, and the real-time vintages allow such studies to use the information that was available at the time.45Two cautions accompany these uses. The index measures the price of a constant basket in the observable attributes; renovations and unobserved quality improvements are in the index, not out of it, and the comparison with the CREA benchmark index in Section~\ref{sec:validation} suggests that this matters for houses in Montréal. And the intervals are model-based and, for mid-sized municipalities, narrower than a cluster bootstrap by a factor of about \BootRatioLevelMedian{} (Table~\ref{tab:bootstrap}); users who need conservative inference should widen them accordingly.6