Data Sources & Methodology
Every metric on homestats.app comes from a public dataset you can verify yourself. This page lists every source we use, the formula behind every derived metric, and other reputable sites worth cross-referencing.
Primary Data Sources
All data is public domain or used under each agency's open-data terms with attribution. Pipeline source code: scripts/fetch-data.mjs.
| Source | What we pull | Grain | Update cadence |
|---|---|---|---|
| Redfin Data Center | Median sale price, inventory, days on market, price drops, sale-to-list ratio, homes sold, months of supply — split by All Residential / Single Family / Condo | National, state, county, city, ZIP | Weekly TSV refresh |
| FRED (St. Louis Fed) | 30-yr + 15-yr mortgage rates (MORTGAGE30US, MORTGAGE15US), serious delinquency (DRSFRMACBS), housing starts (HOUST), existing home sales, unemployment (UNRATE), CPI (CPIAUCSL); state permits (XXBPPRIV) and state unemployment (XXUR) | National + 50 states | Daily–monthly depending on series |
| FHFA House Price Index | Quarterly HPI, mortgage performance | National + state | Quarterly |
| Census ACS 5-year | B19013 (income), B01003 (population), B25002 (vacancy), B25003 (tenure), B25034 (year built), B25007 (homeowner age), B07001 (mobility) | State + 3,142 counties | Annual ACS release |
| HUD Fair Market Rents | Studio / 1BR / 2BR / 3BR / 4BR FMRs | State + metro | Annual (FY) |
| BEA Regional Price Parities | Cost-of-living index relative to U.S. = 100 | State | Annual |
| FBI UCR / Crime Data Explorer | Violent + property crime rates per 100,000 | State (UCR 2022 fallback when API down) | Annual |
| EPA SDWIS | Drinking water quality violations | State | Quarterly |
| FEMA National Risk Index | 18 natural hazard types, expected annual loss | State + county | Periodic refresh |
| FEMA NFIP | Flood insurance policies + claims totals | State | OpenFEMA continuous |
| FEMA Disaster Declarations | Federally declared disaster counts | State | OpenFEMA continuous |
| EIA | Residential electricity prices ($/kWh) | State | Monthly |
| NOAA Climate | Climate normals, average annual temperature | State | 30-year normal |
| Zillow ZORI | Observed Rent Index, smoothed all-homes (metro CSV → state mean) | Metro → state rollup | Monthly |
| NAIC | Average homeowners insurance premium | State (static table) | Annual |
| Tax Foundation | Effective property tax rates | State (static table) | Annual |
| IRS SOI Migration | Net inflow / outflow + top inbound/outbound states (state pages only) | State (static table) | Annual |
| BLS OES | Occupational employment + wages by state | State | Annual |
Derived Metrics — Formulas
Anything we calculate is shown here so you can reproduce it.
- Value / Income = median sale price ÷ median household income. Healthy 3–4×; stretched ≥ 5×; severely overvalued ≥ 6×.
- Value / Rent = median sale price ÷ (Zillow ZORI monthly rent × 12). Investor-friendly < 15×; stretched > 20×; price not supported by rents > 25×.
- Buy-vs-Rent Ratio = monthly PITI ÷ monthly ZORI rent. PITI uses 80% LTV, 6.5% baseline 30-yr fixed, 1.2% effective property tax, 0.5% insurance. < 1.0× = buying cheaper than renting.
- SFR-vs-Condo Gap = SFR YoY price change − Condo YoY price change. Positive = single-family outperforming condos; widely positive often signals condo-specific stress (HOA, insurance, lending).
- Inventory Surplus % = (current inventory − long-term average inventory for that geography) ÷ long-term average. > 0.10 = surplus, buyer leverage; < -0.10 = deficit.
- DOM Spike % = (current days-on-market − trailing 24-month average) ÷ 24-month average. > 0.20 with DOM ≥ 60 days = seller-distress signal.
- HomeStats Market Score = composite 0–100 from DOM, price-cut %, sale-to-list ratio, inventory trend, YoY price change. Higher = more buyer-friendly.
- Boomer / Millennial Owner Share = ACS B25007 owner-occupied householders age 65+ (or 35–54) ÷ all owner-occupied householders.
Other Reputable Sites Worth Cross-Referencing
Different cuts of the same underlying data — useful when you want a second opinion, a different visualization, or proprietary scoring. We have no relationship with any of these. Linking for research transparency only.
| Site | What it offers | Pricing |
|---|---|---|
| Reventure App | Nick Gerli's housing dashboard with proprietary Crash Risk Score, Buyer Demand Score, ZIP-level forecasts, migration heat maps | Subscription |
| NeighborhoodScout | Neighborhood-level appreciation history, school + crime detail, demographic profiles, real-estate-investment scores | Subscription |
| Zillow Research | ZHVI, ZORI, market reports, methodology PDFs, market heat index | Free |
| Realtor.com Economic Research | Active inventory, listing trends, hottest markets ranking | Free |
| ATTOM Data | Foreclosure activity, investor share, cash sales | Paid (cited by reporters) |
| CoreLogic Intelligence | HPI, delinquency, fraud risk, climate risk | Paid |
| ICE / Black Knight Mortgage Monitor | Monthly mortgage performance, servicing data | Free PDFs |
| Harvard JCHS | State of the Nation's Housing annual report | Free |
| NAHB Economics | Builder sentiment, regional starts, cost surveys | Free |
| NAHB Eye on Housing | NAHB economist blog, permits + starts deep-dives | Free |
| Calculated Risk | Bill McBride's housing-data commentary, weekly inventory tracking | Free |
| Altos Research | Weekly active-market data, listing-side metrics, video analyses | Free + paid |
| Parcl Labs | Daily price indices and inventory by market | Free + paid |
| Census SAHIE / SAIPE | Small-area health insurance + income/poverty estimates by county | Free |
| Urban Institute Housing Finance Policy Center | Monthly Housing Finance Chartbook, mortgage performance research | Free |
What We Don't Have (Yet)
- Investor / cash-buyer share at the local level — requires ATTOM, CoreLogic, or PropMix licensing. Free public sources don't publish it at granularity below the metro level.
- County-level mortgage delinquency — FRED has national + state series; county requires CoreLogic / Black Knight.
- School ratings — GreatSchools is the de-facto source and requires a partnership.
- Walk Score / Transit Score — requires a Walk Score API license.
- Proprietary composite forecasts — our position is that transparent metrics (DOM spike, inventory surplus, value ratios, SFR-vs-condo gap) are easier to verify than black-box composite scores. We may add a HomeStats composite later, but we'll publish the formula.
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