Revealed spatial preference scales are the most general way of measuring the degree of individual choice unanimity between alternatives in revealed spatial interaction data. From an examination of the information theoretic content of these scales, a continuous transform of scale differences into predicted choice probabilities is derived, as well as a ratio measure of spatial equity, or a measure of the differences in the quality of facility provision for groups of individuals. It is not necessary to assume that the functions involved are monotonic, additive, or independent of other choices that are known to have been made, and the personal attributes of the decisionmakers.