Median Voter Theorem

The median voter theorem states "a majority rule voting system will select the outcome most preferred by the median voter."

As with every economic model, the median voter theorem makes several assumptions. First, the theorem assumes voters can place all election alternatives along a one-dimensional political spectrum. It seems plausible that voters can do this if they are voting for a single policy or if they can clearly place political candidates on a left to right continuum. However, problems arise if there are multiple policies being considered on the referendum, thus making the continuum multi-dimensional. Second, the theorem assumes that voter’s preferences are single-peaked, which means that voters choose alternatives closest to their most preferred outcome. This assumption predicts that the further away the outcome is from the voter’s most preferred outcome, the less likely the voter is to select that alternative. Third, the median voter theorem assumes that voters always vote for their true preferences. It is clear from the research that voters do not always do this (McKelvey 1976). Finally, the median voter theorem applies best to majoritarian election system.