In political science and social choice theory, the spatial (sometimes ideological or ideal-point) model of voting, also known as the hotelling–downs model, is a mathematical model of voting. Candidate models are specified and compared using training data, after which the best or selected candidate model must be validated, ideally on an independent test set of data to. Building the set of candidate models is partially subjective--that is why scientists are trained, educated and experienced in their discipline.

The citizen candidate approach provides added realism to models of endoge-nous policy formation, and represents a significant advance over the traditional median voter model. When there is a small cost to becoming a candidate, the model churns out three one-candidate equilibria, with no indication which of the three possible equilibria will prevail.