The Electoral College : A Majority Efficiency Analysis. Vincent R. Merlin,∗ Thomas G. Senn´ey Preliminary Version The 29th of January 2008 One of the main topics of voting theory is the assessment of paradox proba- bilities in order to compare different voting rules. These computations are based upon assumptions on the probability distribution of voters' preferences. The two principal hypothesis are the Impartial Culture assumption which stipulates that every voter picks his preference among a set of uniformly distributed orderings, and the Impartial Anonymous Culture which states that every voting situation has the same probability to occur. Their main disadvantage is that they are theoretical a priori models and they do not necessarily match the reality. In this paper we propose to calibrate these usual models in order to assess the probability of the referendum paradox, that is, the probability that the popular winner does not obtain a majority of delegates. Indeed, one of the motivation of this paper is to take part of the debate resulting from the criticisms instated by authors such as Gelman et alii [11, 12] and Regenwetter [26]. In this way, we provide a serie of estimations for the referendum paradox probability in the Electoral College according to a continuum of probabilistic models, which more and more match the real data. The second motivation is to use these different probability assumptions in order to study the current seat allocation method in comparison with apportionment methods. Keywords : Voting, IAC, IC, Referendum Paradox, Majority Efficiency, Electoral College. JEL classification : D71. ∗corresponding author : CREM, Universit´ede Caen, 14032 Caen Cedex, France (email:
[email protected], tel: 02 31 56 62 49) yCREM, Universit´ede Caen, 14032 Caen Cedex, France (email:
[email protected]) 1 1 Introduction During Summer 2000, just before the US presidential elections, at APSA's annual Meeting, numerous political scientists predicted a Democratic (Al Gore) victory by upwards of 6 percentage points.