PARTICIPATORY BUDGETING

Joanna Paszkowska What is PB?

Participatory budgeting (PB) - a democratic process in which community members decide how to spend part of a public budget.

➔ Every citizen can vote directly.

➔ Community-based Indirect participation - decisions are made by delegations or leaders. History

● 1989, (Brazil) - first PB

● By 2001 - more than 100 cities in Brazil had implemented PB

● 2011, Sopot - first PB in Poland How it works? Participatory budgeting algorithm

1. Divisible - allocates any amount of money to any project so that the total sum equals to the budget. 2. Indivisible - each selected project receives amount of money that covers its total cost, total sum does not exceed the budget.

Input: list of projects (+ their costs for indivisible algorithms), total available budget, voting results

Output: partition of budget among the projects Voting formats

1. Approval voting 2. k-approval voting 3. Threshold approval voting 4. Ranked voting 5. Knapsack voting 6. Value-for-money ranking Knapsack problem

Goal: maximize with

where W - total budget n - number of potential projects vⱼ - voting results for project j wⱼ - project j cost

Most common algorithms: ● Greedy solution to Knapsack problem ● Diverse knapsack Majority budgeting

Goal: Satisfy Condorcet criterion (there is no better budget partition than selected one).

➔ There is a polynomial-time algorithm that finds such a budget.

➔ It uses Schwartz sets (union of Schwartz components) - if a Condorcet winner exists, it it the only member of a Schwartz set. Proportional budgeting

➔ For sufficiently large number of votes, the project receives proportional amount of money.

➔ In approval-based multi-winner voting, there is a series of algorithms that generalize the JR (justified representation) and PJR (proportional justified representation) axioms. ➔ Strong Budget-Proportional-Justified-Representation and Budget-Justified-Representation

➔ NP-hard to compute ➔ Does not always exist ◆ {n1, n2}, {k1, k2}, w(k1/k2) = 2, L = 3; n1 votes for k1, n2 votes for k2 ◆ (votes for k1/k2 =) 1 > ⅔ (=n/L), so both projects are chosen, but their cost = 4 > L ➔ Weak Budget-Proportional-Justified-Representation and Budget-Justified-Representation

➔ NP-hard to compute ➔ Always exists PB in Poland

Number of people voting in PB from 6 biggest cities in Poland Money for PB project in Warsaw (in mln zl) (Warsaw, Cracow, Lodz, Wroclaw, Poznan, Gdansk) Frequency from 2018 PB votings in main cities Money spent on PB project per capita (in zl) Warsaw 2020 projects Advantages

● Government

● Citizens can directly decide about their city and present their ideas

● Improvement in citizens’ well-being

● Anyone can vote, also children or teenagers

● Help the citizens to understand the limitations of local government and get more knowledge on designing process and costs for projects Disadvantages

● May act as an illusion - citizens think that they have real power over money while they decide only about ~1% of budget

● It can distract citizens from real problems

● Clientelism

● Spending money on trivial problem

● Can be easily hijacked by the government Bibliography

● https://www.participatorybudgeting.org ● https://app.twojbudzet.um.warszawa.pl ● https://www.miasto2077.pl/wp-content/uploads/2019/03/Raport-Budz%CC%87ety-Obywatelsk ie-w-polskich-miastach.pdf ● https://en.wikipedia.org/wiki/Participatory_budgeting_algorithm ● https://en.wikipedia.org/wiki/Participatory_budgeting ● https://journals.sagepub.com/doi/pdf/10.1177/095624780401600104 ● https://en.wikipedia.org/wiki/Participatory_budgeting_algorithm ● http://www.cse.unsw.edu.au/~haziz/pb_report.pdf