12th Economics & Finance Conference, Dubrovnik

SPECIFIC TASTES OR CLIQUES OF JURORS?

KRZYSZTOF KONTEK

Abstract:

In this paper we first analyze real voting results in the 2016 Henryk Wieniawski International Violin Competition in which the Borda count was adopted to determine the final ranking of contestants. We show that some jurors are suspected of having exploited the weakness in the method to manipulate the final results. We then consider modifications of the standard Borda count aiming to design a method most resistant to manipulation. We show that discarding all the scores of the 20% of jurors who deviate most with their scores from the jury average gives the ranking which agrees with the opinion of the public and of many experts. Modifications of the Borda count were then experimentally tested against their robustness to manipulability. The results clearly show that excluding jurors has very good statistical properties to recover the objective order of the contestants. Most importantly, however, it reduces dramatically the level of manipulation demonstrated by subjects playing the role of jurors. Finally, we present mathematical properties of the method proposed. We show, that the method with 20% of jurors excluded is a compromise between the Majority Criterion and the standard Borda count: it offers more “consensus-based” rankings than the former method while being less vulnerable to manipulation than the latter one. The method proposed in this paper may be applied not only in musical competitions but in many other votes in which the Borda count is usually adopted: elections by educational institutions or professional and technical societies, granting sport awards, and even some political elections.

Keywords: Social choice, voting systems, manipulability of voting results, Borda count

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