% Author: Simon-Pierre Boucher — contact@spboucher.ai
% ============================================================================
\section{Data}
\label{sec:data}

\subsection{Sources}

We use a registry of 745{,}119 Quebec residential-market transactions
recorded between January 2021 and July 2026 --- sale price, date, address
and coordinates --- each matched at the parcel level to the municipal
assessment roll in force at the sale date (median match distance
0.6~metres, validated against the roll's recorded value). The roll
contributes the structural descriptors that are notoriously missing from
transaction registries: total floor area, lot area, year of construction,
number of dwelling units, number of storeys, physical configuration
(detached, semi-detached, row, apartment-linked) and the standardized use
code. This combination --- market prices with assessor-grade structure
for half a million sales across an entire province --- is what makes a
controlled specification race feasible: every model sees exactly the same
attributes.

\subsection{Sample}

We keep residential use codes (dwellings, cottages, mobile homes), require
a high-confidence roll match (distance $\le 50$~m, score $\ge 150$), a
price of at least \$50{,}000, a plausible floor area (20--2{,}000~m$^2$)
and a known year of construction, and trim prices and floor areas at the
1st and 99th percentiles within each sale year. The estimation sample
contains \textbf{514{,}212 sales}: 348{,}253 single-family homes, 75{,}734
condominiums, 74{,}909 plexes (2--5 units), 10{,}349 cottages and 4{,}881
mobile homes, spread over 1{,}115 municipalities, 5{,}255 grid cells of
$\sim$5.5~km and 30{,}548 cells of $\sim$1.1~km.
Table~\ref{tab:sumstats} reports the descriptives. Prices average
\$462{,}000 (median \$399{,}000); the window covers the tail of the
post-pandemic boom, the 2022--2023 rate correction and the subsequent
recovery --- a demanding environment for any static price model, which we
exploit in the forward-in-time evaluation.

\begin{table}[t]
\centering
\begin{threeparttable}
\caption{Summary statistics, estimation sample}
\label{tab:sumstats}
\small
\input{../results/tables/summary_stats}
\begin{tablenotes}[flushleft]\footnotesize
\item \textit{Notes:} 514{,}212 residential sales, January 2021 -- July
2026. Structural descriptors from the assessment roll in force at the
sale date. Lot area is zero for condominiums and other units without an
exclusive lot.
\end{tablenotes}
\end{threeparttable}
\end{table}