Compare methods

	Probabilistic Voting Model	Median Voter Model
Field	Political Economy	Political Economy
Family	MCDM	MCDM
Year of origin	1987	1948
Originator	Assar Lindbeck, Jörgen Weibull & Peter Coughlin	Duncan Black & Anthony Downs
Type	Formal model of electoral competition	Formal model of electoral competition
Seminal source	Lindbeck, A., & Weibull, J. W. (1987). Balanced-budget redistribution as the outcome of political competition. Public Choice, 52(3), 273-297.	Black, D. (1948). On the Rationale of Group Decision-making. Journal of Political Economy, 56(1), 23-34.
Aliases	Probabilistic Voting Theory, Lindbeck-Weibull Model, Coughlin Probabilistic Voting Model, Stochastic Voting Model	Median Voter Theorem, Black's Median Voter Theorem, Downsian Median Voter Model, Median Voter Equilibrium
Related	4	4
Summary	The probabilistic voting model is a formal theory of electoral competition in which each voter's choice between two parties is treated as stochastic rather than deterministic, governed by a smooth probability that depends on the policy utilities the parties offer plus idiosyncratic and partisan preference shocks. Developed by Assar Lindbeck and Jörgen Weibull in 1987 and given its general treatment by Peter Coughlin in 1992, the model replaces the knife-edge switching of the median voter framework with continuous vote-share functions. Two office-seeking parties maximize expected vote share, and the resulting equilibrium maximizes a density-weighted social welfare function in which the most responsive — the swing — voters carry the greatest weight. Crucially, the model delivers a determinate, interior equilibrium even in multidimensional policy spaces where a Condorcet winner generically fails to exist.	The median voter model is a foundational result of political economy stating that, under majority rule with voters whose preferences are single-peaked on a single policy dimension, the ideal point of the median voter is the Condorcet winner — it cannot be beaten by any other alternative in pairwise majority voting. Duncan Black established the theorem formally in 1948, and Anthony Downs extended it in 1957 into a theory of party competition in which two vote-maximizing parties converge to the median voter's preferred policy. The model is the workhorse linking the distribution of citizen preferences to equilibrium policy outcomes in democracies.