Developers
API reference, data dictionary, MCP catalog, and the MCP connection guide.
Chicago Value Map — Cook + Lake County investment intelligence
The numbers are the brand — every score ships with its published error rate, an as-of date, and an honest "unscored" when the data is thin.
20.1%median ARV error (MdAPE)
50%sales within ±20% (PPE20)
+4.7%bias (model runs hot)
–deals graded vs model
Published baseline: backtest v0, 744 arms-length 2–4 unit resales, leave-one-out, as-of 2026-06.
What this is
Section titled “What this is”Tract-level signals for Cook and Lake County, Illinois: flip and BRRRR scores, effective tax and reassessment shock, Section 8 arbitrage, comp-based ARV with published error rates, and full-stack underwriting. Automated valuation model — not an appraisal; outputs may not be used for tenant screening or credit decisions (FCRA).
Methodology
Accuracy — the backtest behind every number — and limitations, which you should read first.
Legal
Data attributions and terms of use for served data.