A comparison of theoretical and empirical evaluations of the Borda Compromise

The Borda Compromise states that, if one has to choose among five popular voting rules that are not Condorcet consistent, one should always give preference to the Borda rule over the four other rules. We assess the theoretical as well as the empirical support for the Borda Compromise. We find that, despite considerable differences between the properties of the theoretical framework and the characteristics of two sets of observed ranking data, all three analyses provide considerable support for the Borda Compromise.     

Obtaining representations for probabilities of voting outcomes with effectively unlimited precision integer arithmetic

A procedure is developed to obtain representations for the probability of election outcomes with the Impartial Anonymous Culture Condition and the Maximal Culture Condition. The procedure is based upon a process of performing arithmetic with integers, while maintaining absolute precision with very large integer numbers. The procedure is then used to develop probability representations for a number of different voting outcomes, which have to date been considered to be intractable to obtain with the use of standard algebraic techniques. Received: 13 June 2000/Accepted: 22 January 2001     

Bayesian tests for matched proportions

A sample of n subjects is observed in each of two states, S₁-and S₂. In each state, a subject is in one of two conditions, X or Y. Thus, a subject may be recorded as showing a change if its condition in the two states is ‘Y,X’ or ‘X,Y’ and, otherwise, the condition is unchanged. We consider a Bayesian test of the null hypothesis that the probability of an ‘X,Y’ change exceeds that of a ‘Y,X’ change by amount k_O. That is, we develop the posterior distribution of k_O, the difference between the two probabilities and reject the null hypothesis if k lies outside the appropriate posterior probability interval. The performance of the method is assessed by Monte Carlo and other numerical studies and brief tables of exact critical values are presented     

Powers of subgroups in voting bodies

This paper discusses the power p _n of an n-member subgroup B _n of an N-member voting body, N odd and 1 n N. In contrast to bloc voting, we assume that the members vote independently with equal probability for and against a given issue. Power p _n is defined as the probability that the outcome of a vote changes if all members of B _n reverse their votes. Theorems: p _{n + 1} = _n for odd n < N; p _n + p _{N – n} = 1; P _m + p _n > p _{m + n} if m + n < N; p _{n + 1}/p _n (n + 1)/n as N for fixed even n; for rational 0 > > 1, p _N 2^–1 sin^{–1 1/2} as N . A simple summation formula is given for p _n .     

The effect of social homogeneity on coincidence probabilities for pairwise proportional lottery and simple majority rules

The Condorcet efficiency of Pairwise Proportional Lottery Rules (PPLR) is considered under various assumptions concerning the likelihood that given voters' preference profiles are observed on three alternatives. Representations are developed for the expected Condorcet efficiency under impartial culture, impartial anonymous culture, and a generalization to Pólya-Eggenberger distributions. PPLR is shown to be equivalent to a random selection process in the limit of voters under impartial culture. However, relatively small increases in social homogeneity, as measured by Kendall's Coefficient of Concordance, cause significant increases in the Condorcet efficiency of PPLR.Professor Berg's work was partly supported by the Swedish Research Council for the Humanities and Social Sciences.     

Which Scoring Rule Maximizes Condorcet Efficiency Under Iac?

Consider an election in which each of the n voters casts a vote consisting of a strict preference ranking of the three candidates A, B, and C. In the limit as n→∞, which scoring rule maximizes, under the assumption of Impartial Anonymous Culture (uniform probability distribution over profiles), the probability that the Condorcet candidate wins the election, given that a Condorcet candidate exists? We produce an analytic solution, which is not the Borda Count. Our result agrees with recent numerical results from two independent studies, and contradicts a published result of Van Newenhizen (Economic Theory 2, 69–83. (1992)).