Reference
Glossary
Short definitions of every metric and dataset used on HousingHandbook, alphabetized. For the longer-form versions, see articles and methodology.
- #ACS (American Community Survey)
- The US Census Bureau's rolling 5-year household survey. Source of population, median household income, and aggregate real-estate-tax data for the effective property-tax rate. Suppressed for very small ZIPs to protect respondent privacy.
- See also: Effective property tax rate, Population
- #CAGR (compound annual growth rate)
- The constant annual rate that, compounded over a period, takes a start value to an end value. Used for 5-year and 10-year home-value appreciation: (latest / earlier)^(1/years) − 1.
- See also: ZHVI
- #Cap rate (capitalization rate)
- Net operating income divided by purchase price, as a fraction. We estimate net operating income by subtracting 40% of gross rent for taxes, insurance, repairs, vacancy, and management — the standard rule of thumb for single-family rentals.
- See also: Gross rental yield, ZORI
- #Climate risk (FEMA National Risk Index)
- FEMA's composite rating for a county's natural-hazard exposure, plus per-hazard ratings (riverine flood, coastal flood, wildfire, drought, heat wave, hurricane, tornado, earthquake, winter weather). County-level — every ZIP in a county shares the same rating; intra-county variation (one floodplain ZIP, one bluff-top ZIP) is not captured. Currently pinned to release v1.20.
- See also: ZCTA
- #Effective property tax rate
- Aggregate real-estate taxes paid in a ZIP divided by aggregate home value, both from the latest Census ACS 5-year. Includes every assessment line item — not the headline statutory rate. Applied to the typical home value to estimate a ZIP-median annual tax bill.
- See also: ACS, ZHVI
- #Gross rental yield
- Annual rent (latest ZORI × 12) divided by typical home value (latest ZHVI), as a fraction. A cash-flow proxy that ignores expenses, vacancy, and financing — use cap rate for an estimate net of expenses.
- See also: ZHVI, ZORI, Cap rate
- #IRS SOI migration data
- County-to-county migration counts derived from year-over-year address changes on tax returns, published annually by the IRS Statistics of Income with roughly an 18-month lag. Returns ≠ people (one return can be a couple, a family, or a single filer). Aggregate only — county-level, not ZIP-level.
- See also: Population
- #Median household income
- The middle household income in a ZIP, from the latest ACS 5-year estimates. Suppressed for very small ZIPs.
- See also: ACS
- #NCES Common Core of Data
- The US Department of Education's universe of open public schools — name, level, grade range, district, and enrollment. Public schools only; private and charter-but-not-public-funded schools are excluded. Updated annually.
- #Net migration
- Inflow returns minus outflow returns over a tax year, from the IRS SOI dataset. Positive means more households moved into the county than left.
- See also: IRS SOI migration data
- #Population (ZIP)
- Total residents in a ZIP, from the latest ACS 5-year estimates. Used as the weighting factor when rolling ZIP data up to city, county, metro, and state aggregates.
- See also: ACS, Population-weighted median
- #Population-weighted median
- An aggregation method where each ZIP's value is weighted by its population before computing the median. Matches how Zillow Research and FHFA roll ZIP indices up to higher geographies — see /methodology.
- See also: ZHVI, ZORI
- #Typical home value
- A modeled estimate of the middle-of-the-market home value in a ZIP — what Zillow calls the 35th-to-65th-percentile home. Tracks the typical home in a market, not the average sale. Our default home-value metric site-wide.
- See also: ZHVI
- #Yoy (year-over-year)
- The 12-month change in a metric, as a fraction (e.g. 0.124 = +12.4%). For home values, this is (latest ZHVI / ZHVI 12 months earlier) − 1.
- See also: ZHVI, CAGR
- #ZCTA (ZIP Code Tabulation Area)
- The US Census Bureau's geographic approximation of a USPS ZIP code. ZCTAs don't match USPS ZIPs perfectly — the USPS reorganizes ZIPs more often than Census redraws ZCTAs — but they're the canonical source for ZIP-level data analysis.
- #ZHVI (Zillow Home Value Index)
- Zillow's monthly typical-home-value series, smoothed and seasonally adjusted, for every ZIP with sufficient sales data. Tracks the 35th–65th-percentile home, so very-high and very-low priced ZIPs in a market are compared on the same scale. Updated monthly.
- See also: Typical home value, Yoy, CAGR
- #ZORI (Zillow Observed Rent Index)
- Zillow's monthly typical asking-rent series, for every ZIP with sufficient listing volume. Some rural and very-small ZIPs have no ZORI because the sample is too thin — we hide rental metrics on those pages rather than estimate.
- See also: Gross rental yield, Cap rate