Divisor-Based Biproportional Apportionment in Electoral Systems: A Real-Life Benchmark Study

• 成果类型: Article
• 署名作者: Maier, Sebastian; Zachariassen, Petur; Zachariasen, Martin
• 署名单位: University of Augsburg; University of Copenhagen
• 刊物名称: MANAGEMENT SCIENCE
• ISSN/ISSBN: 0025-1909
• DOI: 10.1287/mnsc.1090.1118
• 发表日期: 2010
• 页码: 373-387
• 关键词: Electoral systems; divisor-based biproportional apportionment; computer simulation

摘要

Biproportional apportionment methods provide two-way proportionality in electoral systems where the electoral region is subdivided into electoral districts. The problem is to assign integral values to the elements of a matrix that are proportional to a given input matrix, and such that a set of row-and column-sum requirements are fulfilled. In a divisor-based method for biproportional apportionment, the problem is solved by computing appropriate row and column divisors, and by rounding the quotients. We present a comprehensive experimental evaluation of divisor-based biproportional apportionment in an electoral system context. By performing experiments on real-life benchmark instances (election data with multimember districts), we evaluate the general quality of divisor-based apportionments with respect to, e. g., deviation from quota, reversal orderings, and occurrences of ties. For example, we studied the frequency in which a party with a higher vote count in a district ended up with fewer seats in that district.