# QWHPI validation report ## 1. Repeat-sales (BMN) vs hedonic index - quebec/unifamilial: Δcorr=0.691, end levels RS=161.5 vs hedonic=157.9 - quebec/condo: Δcorr=0.322, end levels RS=133.8 vs hedonic=140.0 - quebec/plex: Δcorr=0.454, end levels RS=149.6 vs hedonic=158.5 - montreal/condo: Δcorr=0.000, end levels RS=121.8 vs hedonic=128.7 - montreal/unifamilial: Δcorr=0.264, end levels RS=125.6 vs hedonic=132.8 - quebec-city/unifamilial: Δcorr=0.073, end levels RS=165.7 vs hedonic=166.0 ## 2. Downsampling experiment — Montréal condo lab - 100 tx/wk: RMSE=0.317% bias=-0.046% vol_ratio=1.051 turn_agree=0.861 CI95_cov=1.0 - 50 tx/wk: RMSE=0.636% bias=-0.177% vol_ratio=0.987 turn_agree=0.799 CI95_cov=0.992 - 25 tx/wk: RMSE=0.799% bias=0.002% vol_ratio=0.762 turn_agree=0.771 CI95_cov=0.977 - 15 tx/wk: RMSE=1.15% bias=-0.154% vol_ratio=0.449 turn_agree=0.778 CI95_cov=0.881 - 10 tx/wk: RMSE=1.361% bias=-0.18% vol_ratio=0.358 turn_agree=0.735 CI95_cov=0.828 - 5 tx/wk: RMSE=1.633% bias=0.189% vol_ratio=0.457 turn_agree=0.685 CI95_cov=0.856 Reading: RMSE vs the full-sample (~145 tx/wk) smoothed path; CI coverage of the deviation posterior; turning points on 4-week MA. ## 3. Composition-shock simulation (province unifamilial) - Shock: drop 70% of below-median floorArea sales in 2024-H1 (12,406 of 439,118 rows removed) - Raw weekly median moves by +11.74% in shocked weeks (must move) - Hedonic time-dummy moves by -0.74% (must stay ~0) ## 4. Weekly vs monthly (same methodology) - quebec/unifamilial: weekly signal SD=3.665%, noise SD=0.0%, monthly ΔSD=3.198%, real-time revision SD=0.0% - quebec/condo: weekly signal SD=3.778%, noise SD=0.0%, monthly ΔSD=2.993%, real-time revision SD=0.0% - montreal/condo: weekly signal SD=3.782%, noise SD=3.583%, monthly ΔSD=3.031%, real-time revision SD=3.999%