1. A server-device-implemented method for optimizing training data for developing a predictive model to automatically value a subject real-estate property, the method comprising: obtaining, by one or more server devices, an indication to provide an automated value prediction for the subject real-estate property as of an effective date; in response to obtaining said indication, defining, by said server device, a search space having multiple dimensions, each corresponding to a range of candidate values for a search criterion for selecting subsets of a multiplicity of sales-transaction records, said multiple dimensions including at least a temporal dimension that measures distance in time before the effective date, and a geographic dimension that measures distance in space away from the subject real-estate property; evaluating, by said one or more server devices, a multiplicity of points within said multi-dimension search space, said multiplicity of points varying along at least said temporal dimension and said geographic dimension; selecting, by said one or more server devices based at least in part on evaluating said multiplicity of points within said multi-dimension search space, a first majority subset of said multiplicity of sales-transaction records as a first statistical accuracy data structure according to a first search criteria set; developing, by said one or more server devices, the predictive model according to said first majority subset of said multiplicity of sales-transaction records; obtaining, by said one or more server devices, a first statistical measure of the predictive model applied to said first majority subset of said multiplicity of sales-transaction records; selecting, by said one or more server devices based at least in part on evaluating said multiplicity of points within said multi-dimension search space, a second majority subset of said multiplicity of sales-transaction records as a second statistical accuracy data structure according to a second search criteria set; developing, by said one or more server devices, the predictive model according to said second majority subset of said multiplicity of sales-transaction records; obtaining, by said one or more server devices, a second statistical measure of the predictive model applied to said second majority subset of said multiplicity of sales-transaction records; determining that the second statistical measure of the predictive model applied to said second majority subset of said multiplicity of sales-transaction records indicates greater accuracy than the first statistical measure of the predictive model applied to said first majority subset of said multiplicity of sales-transaction records; and developing, by said one or more server devices in response to said greater accuracy, the predictive model according to said second subset of said multiplicity of sales-transaction records to generate said automated value prediction for the subject real-estate property as of the effective date.