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QHPI — Quebec Housing Price Index: quality-adjusted, hierarchically pooled housing price indexes.

🔗 https://www.indexqc.house
webappreal-estatequebecindexeconometrics
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# 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%