Proportionality Degree in Participatory Budgeting
New paper provides first mathematical framework to measure 'proportionality degree' in participatory budgeting.
A team of computer scientists has published a foundational paper introducing the concept of 'proportionality degree' to the field of participatory budgeting. This research, led by Aris Filos-Ratsikas, Sreedurga Gogulapati, and Georgios Kalantzis, provides the first quantitative framework for measuring how fairly different voting methods allocate public funds when citizens directly decide on budget projects. The study focuses on two widely-used methods: the Method of Equal Shares (MES) and Phragmén's Sequential Rule.
The researchers derived mathematically tight bounds on the proportionality degree of both methods, revealing a surprising result: despite MES satisfying stronger theoretical fairness guarantees, both rules perform equally well from a quantitative measurement perspective. This finding suggests that while MES might be preferable for its axiomatic properties, Phragmén's rule offers comparable practical fairness. The team complemented their theoretical analysis with extensive experiments on real-world participatory budgeting datasets, with results that closely mirrored their mathematical predictions, providing empirical validation for their framework.
- Establishes first quantitative metric ('proportionality degree') for measuring fairness in participatory budgeting systems
- Finds Method of Equal Shares and Phragmén's Sequential Rule have identical proportionality bounds despite different theoretical properties
- Validates theoretical findings with extensive experiments on real-world datasets from actual participatory budgeting implementations
Why It Matters
Provides cities and organizations with mathematical tools to choose fairer voting systems for allocating public funds democratically.