While proportionality is frequently named as a desirable property of voting rules, its interpretation in multiwinner voting differs significantly from that in apportionment. We aim to bridge these two distinct notions of proportionality by introducing the concept of allocation proportionality, founded upon the framework of party elections, where each candidate in a multiwinner election is assigned to a party. A voting rule is allocation proportional if each party's share of elected candidates equals that party's aggregate score. Recognizing that no committee scoring rule can universally satisfy allocation proportionality in practice, we introduce a new measure of allocation proportionality degree and discuss how it relates to other quantitative measures of proportionality. This measure allows us to compare OWA-based committee scoring rules according to how much they diverge from the ideal of allocation proportionality. We present experimental results for several common rules: SNTV, $k$-Borda, Chamberlin-Courant, Harmonic Borda, Proportional $k$-Approval Voting, and Bloc Voting.

翻译：尽管比例性常被视为投票规则的一项理想属性，但其在多席位选举中的含义与席位分配中的解释存在显著差异。本文旨在通过引入席位分配比例性的概念来弥合这两种不同的比例性观念，该概念建立在政党选举框架之上，其中多席位选举中的每位候选人均归属于某一政党。若一个投票规则能使各政党当选候选人的比例等于该政党的总得票比例，则称其满足席位分配比例性。认识到实践中不存在能普遍满足席位分配比例性的委员会计分规则，我们引入了一种新的席位分配比例性程度度量方法，并探讨其与其他定量比例性度量指标的关系。该度量方法使我们能够依据与理想席位分配比例性的偏离程度，比较基于有序加权平均（OWA）的委员会计分规则。我们针对多种常见规则给出了实验结果：单记非让渡投票法（SNTV）、$k$-博尔达计分法、钱伯林-库朗特规则、调和博尔达计分法、比例$k$-认可投票法以及集团投票法。