In Participatory Budgeting, cities allow their residents to influence the city’s budget through a vote. The standard voting method simply sorts the project proposals by their number of votes, and then greedily selects projects until the budget limit is reached. We have developed a new voting rule, the Method of Equal Shares, that leads to fairer outcomes. It does this by providing proportional representation. Our method has been used for the first time in 2023 in Wielieczka in Poland, and will be used in Aarau in Switzerland later this year. In this talk, I will explain how the method works and the formal proportionality guarantees it satisfies. I will also show data from simulations: because we have full election data from several cities, we can simulate what would have happened if those cities had used the Method of Equal Shares. Thus, we can compare how well the voters’ preferences are represented by our method compared to the standard method. I will also discuss algorithmic aspects and open problems.
Seminar room 4B125 (Copernic building)
5 Boulevard Descartes 77420 Champs-sur-Marne