The Condorcet efficiency of a social choice procedure is usually defined as the probability that this procedure coincides with the majority winner (or majority ordering) in random samples, given a majority winner exists (or given the majority ordering is transitive). Consequently, it is in effect a conditional probability that two sample statistics coincide, given certain side conditions. We raise a different issue of Condorcet efficiencies: What is the probability that a social choice procedure applied to a sample matches with the (...) majority preferences of the population from which the sample was drawn? We investigate the canonical case where the sample statistic is itself also majority rule and the samples are drawn from real world distributions gathered from national election surveys in Germany, France, and the United States. We relate the results to the existing literature on majority cycles and social homogeneity. We find that these samples rarely display majority cycles, whereas the probability that a sample misrepresents the majority preferences of the underlying population varies dramatically and always exceeds the probability that the sample displays cyclic majority preferences. Social homogeneity plays a fundamental role in the type of Condorcet efficiency investigated here. (shrink)

Although stability is a central notion in several academic disciplines, the parallelsremain unexplored since previous discussions of the concept have been almostexclusively subject-specific. In the literature we have found three basic conceptsof stability, that we call constancy, robustness, and resilience. They are all foundin both the natural and the social sciences. To analyze the three concepts we introducea general formal framework in which stability relates to transitions between states. Itcan then be shown that robustness is a limiting case of resilience, (...) whereas neitherconstancy nor resilience can be defined in terms of the other. Hence, there are twobasic concepts of stability, both of which are used in both the social and the naturalsciences. This congruence in the concepts of stability is of particular interest forendeavours to construct models that represent both natural and social phenomena. (shrink)