Spatiotemporal Model of Real Estate Valuation Trend

Presented here is a model objectivizing real estate prices so that prices across time could be compared to understand historical price trends and also to assist in a property evaluation or appraisal, as well as for the analysis of comparables in estimating a reasonable offer for a property on the market. Given a timespan of interest, a locale (e.g., a particular zipcode, a city, a county, a state), a category of properties of interest (e.g., condos), an objective historical trend in values can be computed by first evaluating the ratios between the transactions' realized prices and objective governmental assessment of the properties at some fixed point of time; then, for each period (a month) averaging the ratios of all transaction in that period; then, comparing said averages (or medians) between different periods.