Participatory budgeting, as a paradigm for democratic innovations, engages citizens in the distribution of a public budget to projects, which they propose and vote for implementation. So far, voting algorithms have been devised and studied in social choice literature to elect projects that are popular, while others prioritize on a proportional representation of voters' preferences, for instance, equal shares. However, the anticipated impact and novelty in the broader society by the winning projects, as selected by different algorithms, remains totally under-explored, lacking both a universal theory of impact for voting and a rigorous framework for impact and novelty assessments. This papers tackles this grand challenge towards new axiomatic foundations for designing effective and fair voting methods. This is via new and striking insights derived from a large-scale analysis of biases over 345 real-world voting outcomes, characterized for the first time by a novel portfolio of impact and novelty metrics. We find strong causal evidence that equal shares comes with impact loss in several infrastructural projects of different cost levels that have been so far over-represented. However, it also comes with a novel, yet over-represented, impact gain in welfare, education and culture. We discuss broader implications of these results and how impact loss can be mitigated at the stage of campaign design and project ideation.

翻译：参与式预算作为民主创新的范式，邀请公民参与公共预算在项目中的分配，这些项目由他们提议并投票实施。迄今为止，社会选择文献中已设计并研究了投票算法，用于选出受欢迎的项目，而其他算法则优先考虑选民偏好的比例代表性，例如均等份额。然而，由不同算法选出的获胜项目在更广泛社会中的预期影响和新颖性仍完全未被充分探索，既缺乏普适的投票影响理论，也缺乏严格的影响和新颖性评估框架。本文致力于应对这一重大挑战，为设计有效且公平的投票方法奠定新的公理基础。这源于对345个真实世界投票结果偏差的大规模分析所得的新颖且引人注目的见解，并首次通过一套新颖的影响和新颖性指标组合进行刻画。我们发现强有力的因果证据表明，均等份额在多个不同成本层级的基础设施项目中导致影响损失，而这些项目此前被过度代表。然而，它也在福利、教育和文化领域带来了新颖但同样过度代表的影响增益。我们讨论了这些结果的更广泛影响，以及如何在竞选设计和项目构思阶段缓解影响损失。