Abstract: Methods, systems and computer-readable medium for enabling improved market value and sales price calculations are provided. In one case, a plurality of data sets are analyzed by a computer to derive a predictive equation. Each data set contains (a.) a sales price of a particular real property; and (b.) a plurality of quantitative parameters of qualities and conditions related to or descriptive of that particular real property. A human analyst then reviews the predictive equation and may modify the equation in light of the analyst's personal knowledge or research of a geographic area or neighborhood comprising the real properties of the data sets. The modified equation may only be applied to a geographic area associated with the human analyst. The invented method may be applied to forecasting and valuations in general, wherein a general valuation equation is computationally generated and an analyst modifies the equation.