House Price Estimator Features Based

This is a hedonic model: it treats a dwelling as a bundle of attributes and assigns an implicit price to each one. The dominant term is location, expressed here as a base price per square foot, because land value and neighborhood characteristics routinely explain more of the variation in sale price than anything about the structure itself. Floor area is then applied with diminishing marginal value - full rate to roughly 1,500 square feet, about 85 percent through the next thousand, then about 70 percent - which reproduces the observed pattern that price per square foot falls as homes get larger. The remaining multipliers encode market convention, not construction cost. Three to four bedrooms is the demand sweet spot in most US markets. A second bathroom is the single largest discrete addition, commonly worth 8 to 10 percent, while each further bathroom adds only 3 to 4 percent. Age is not monotonic: new construction carries a 10 to 15 percent premium, depreciation runs roughly 0.3 to 0.5 percent per year through middle age as roofs, HVAC and plumbing consume their service lives, and genuinely historic stock can recover a premium for character. The carrying-cost figures assume 30-year amortization at 7 percent with 20 percent down, property tax at 1.1 percent and insurance at 0.3 percent - national approximations only, since effective property tax rates range from under 0.4 percent in Hawaii to above 2 percent in New Jersey. Such estimates typically land within 10 to 20 percent of actual sale price and cannot see condition, views, or school attendance boundaries.

The method of pricing a good by its characteristics was developed for cars rather than houses. Andrew Court, working for the Automobile Manufacturers Association in 1939, coined the term hedonic price index while trying to separate quality improvements from genuine price inflation in automobiles. Zvi Griliches revived the approach for the same purpose in the early 1960s, Kelvin Lancaster's 1966 consumer theory recast goods generally as bundles of characteristics, and Sherwin Rosen supplied the equilibrium foundation in his 1974 Journal of Political Economy paper on hedonic prices and implicit markets. Housing became the canonical application because dwellings are highly heterogeneous and transact infrequently, so no simple average price is meaningful. Appraisal practice developed on a separate track. The sales comparison approach, which adjusts recent comparable sales for differences in features, was formalized by US appraisal organizations in the 1930s alongside Federal Housing Administration underwriting. After the savings-and-loan collapse, the Appraisal Foundation was established in 1987 and its Uniform Standards of Professional Appraisal Practice were adopted by federal regulators under FIRREA in 1989. Karl Case and Robert Shiller published their repeat-sales index methodology in 1987, giving markets a way to measure price change without modeling features at all. Automated valuation models merged the two traditions once county assessor records and multiple listing data became machine-readable; Zillow launched the Zestimate in 2006 and now publishes median error rates in the low single digits for homes actively listed for sale.