Participatory budgeting ballot types

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In participatory budgeting, one of the design decisions is what ballot type (input format) will be used for preference elicitation - how each voter should express his or her preferences over the projects. Different cities use different ballot types (see List of participatory budgeting votes), and various experiments have been conducted to assess the advantages and disadvantages of each type.

Contents

Common ballot types

Several input formats used in practice are:

These input formats ignore the different costs of the projects. Some newer input formats, which do consider the costs, are: [4]

A different input format, particularly suited for divisible PB, lets users report their entire ideal budget, that is, specify exactly how much money should be given to each project (see Budget-proposal aggregation).

Comparison

The various input formats can be compared based in terms of implicit utilitarian voting - how much each input-format is useful in maximizing the sum of utilities. From this perspective, threshold approval voting is superior to knapsack voting, ranking-by-value and ranking-by-value-for-money: it minimizes the distortion from the maximum sum-of-utilities both theoretically and empirically. [5]

Several other experiments have been done to compare ballot types (see Participatory budgeting experiments).

Goel, Krishnaswamy, Sakshuwong and Aitamurto [6] report the results of several experiments done on real PB systems in Boston (2015–2016), Cambridge (2014–2015), Vallejo (2015) and New York City (2015). They compare knapsack voting to k-approval voting. Their main findings are:

  1. Knapsack voting tends to favor cheaper projects, whereas k-approval favors more expensive projects. This is probably due to the fact that knapsack voting raises the voters' attention to the project costs.
  2. The time it takes users to vote using the digital interface is not significantly different between the two methods; knapsack voting does not take more time.
  3. Using pairwise comparisons of value-per-money, they conclude that knapsack voting allows voters to better represent their preferences.[ clarification needed ]

Later experiments lead to different conclusions:

Benade, Itzhak, Shah, Procaccia and Gal [7] compared input formats on two dimensions: efficiency (social welfare of the resulting outcomes), and usability (cognitive burden on the voters). They conducted an empirical study with over 1200 voters. Their story was about resource allocation for a desert island. They concluded that k-approval voting imposes low cognitive burden and is efficient, although it is not perceived as such by the voters.

Benade, Nath, Procaccia and Shah [5] experimented with four input formats: knapsack voting, ranking by value, ranking by value-for-money, and threshold-approval. Their goal was to maximize social welfare by using observed votes as proxies for voters’ unknown underlying utilities. They found out that threshold-approval voting performs best on real PB data.

Fairstein, Benade and Gal [8] report the results of an experiment with Amazon Turk workers, on a PB process in an imaginary town. In their experiment, 1800 participants vote in four PB elections in a controlled setting, to evaluate the practical effects of the choice of voting format and aggregation rule. They compared k-approval[ clarification needed ], threshold-approval, knapsack voting, rank by value, rank by value/cost, and cardinal ballots. Their main findings [9] are that the k-approval voting format leads to the best user experience: users spent the least time learning the format and casting their votes, and found the format easiest to use. They felt that this format allowed them to express their preferences best, probably due to its simplicity.

Yang, Hausladen, Peters, Pournaras, Fricker and Helbing [10] constructed an experiment modeled over the PB process in Zurich. They had 180 subjects that are students from Zurich universities. Each subject had to evaluate projects in six input formats: unrestricted approval, 5-approval, 5-approval with ranking, cumulative with 5 points, cumulative with 10 points, cumulative with 10 points over 5 projects. The subjects were then asked which input format was most easy, most expressive, and most suitable. Unrestricted approval was conceived most easy, but least expressive and least suitable; in contrast, 5-approval with ranking, and cumulative with 10 points over 5 projects, were found significantly more expressive and more suitable. Suitability was affected mainly by expressiveness; the effect of easiness was negligible. They also found out that the project ranking in unrestricted approval was significantly different than in the other 5 input formats. Approval voting encouraged voters to disperse their votes beyond their immediate self-interest. This may be considered as altruism, but it may also mean that this format does not represent their preferences well enough.

Related Research Articles

<span class="mw-page-title-main">Approval voting</span> Single-winner electoral system

Approval voting is an electoral system in which voters can select many candidates instead of selecting only one candidate.

Arrow's impossibility theorem, the general possibility theorem or Arrow's paradox is an impossibility theorem in social choice theory that states that when voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide ranking while also meeting the specified set of criteria: unrestricted domain, non-dictatorship, Pareto efficiency, and independence of irrelevant alternatives. The theorem is often cited in discussions of voting theory as it is further interpreted by the Gibbard–Satterthwaite theorem. The theorem is named after economist and Nobel laureate Kenneth Arrow, who demonstrated the theorem in his doctoral thesis and popularized it in his 1951 book Social Choice and Individual Values. The original paper was titled "A Difficulty in the Concept of Social Welfare".

<span class="mw-page-title-main">Participatory budgeting</span>

Participatory budgeting (PB) is a type of citizen sourcing in which ordinary people decide how to allocate part of a municipal or public budget through a process of democratic deliberation and decision-making. Participatory budgeting allows citizens or residents of a locality to identify, discuss, and prioritize public spending projects, and gives them the power to make real decisions about how money is spent.

<span class="mw-page-title-main">Social Choice and Individual Values</span>

Kenneth Arrow's monograph Social Choice and Individual Values and a theorem within it created modern social choice theory, a rigorous melding of social ethics and voting theory with an economic flavor. Somewhat formally, the "social choice" in the title refers to Arrow's representation of how social values from the set of individual orderings would be implemented under the constitution. Less formally, each social choice corresponds to the feasible set of laws passed by a "vote" under the constitution even if not every individual voted in favor of all the laws.

Fair item allocation is a kind of the fair division problem in which the items to divide are discrete rather than continuous. The items have to be divided among several partners who potentially value them differently, and each item has to be given as a whole to a single person. This situation arises in various real-life scenarios:

Implicit utilitarian voting is a voting system in which agents are assumed to have utilities for each alternative, but they express their preferences only by ranking the alternatives. The system tries to select an alternative which maximizes the sum of utilities, as in the utilitarian social choice rule, based only on the ranking information it has been provided. A possible advantage of implicit utilitarian voting over explicit utilitarian voting is that providing only a ranking may be cognitively easier for voters.

Combinatorial participatory budgeting,also called indivisible participatory budgeting or budgeted social choice, is a problem in social choice. There are several candidate projects, each of which has a fixed costs. There is a fixed budget, that cannot cover all these projects. Each voter has different preferences regarding these projects. The goal is to find a budget-allocation - a subset of the projects, with total cost at most the budget, that will be funded. Combinatorial participatory budgeting is the most common form of participatory budgeting.

As of 2015, over 1,500 instances of participatory budgeting (PB) have been implemented across the five continents. While the democratic spirit of PB remains the same throughout the world, institutional variations abound.

Multiwinner approval voting, also called approval-based committee voting, is a multi-winner electoral system that uses approval ballots. Each voter may select ("approve") any number of candidates, and multiple candidates are elected. The number of elected candidates is usually fixed in advance. For example, it can be the number of seats in a country's parliament, or the required number of members in a committee.

Multiwinner voting, also called multiple-winner elections or committee voting or committee elections, is an electoral system in which multiple candidates are elected. The number of elected candidates is usually fixed in advance. For example, it can be the number of seats in a country's parliament, or the required number of members in a committee.

Fractional approval voting is an electoral system using approval ballots, in which the outcome is fractional: for each alternative j there is a fraction pj between 0 and 1, such that the sum of pj is 1. It can be seen as a generalization of approval voting: in the latter, one candidate wins and the other candidates lose. The fractions pj can be interpreted in various ways, depending on the setting. Examples are:

Phragmén's voting rules are rules for multiwinner voting. They allow voters to vote for individual candidates rather than parties, but still guarantee proportional representation. They were published by Lars Edvard Phragmén in French and Swedish between 1893 and 1899, and translated to English by Svante Janson in 2016.

The Method of Equal Shares is a proportional method of counting ballots that applies to participatory budgeting, to committee elections, and to simultaneous public decisions. It can be used when the voters vote via approval ballots, ranked ballots or cardinal ballots. It works by dividing the available budget into equal parts that are assigned to each voter. The method is only allowed to use the budget share of a voter to implement projects that the voter voted for. It then repeatedly finds projects that can be afforded using the budget shares of the supporting voters. In contexts other than participatory budgeting, the method works by equally dividing an abstract budget of "voting power".

Multi-issue voting is a setting in which several issues have to be decided by voting. Multi-issue voting raises several considerations, that are not relevant in single-issue voting.

Budget-proposal aggregation (BPA) is a problem in social choice theory. A group has to decide on how to distribute its budget among several issues. Each group-member has a different idea about what the ideal budget-distribution should be. The problem is how to aggregate the different opinions into a single budget-distribution program.

Donor coordination is a problem in social choice. There are several donors, each of whom wants to donate some money. Each donor supports a different set of targets. The goal is to distribute the total donated amount among the various targets in a way that respects the donors' preferences.

Participatory budgeting experiments are experiments done in the laboratory and in computerized simulations, in order to check various ethical and practical aspects of participatory budgeting. These experiments aim to decide on two main issues:

  1. Front-end: which ballot type to use as an input? See Participatory budgeting ballot types for common types of ballots.
  2. Back-end: Which rule to use for aggregating the voters' preferences? See combinatorial participatory budgeting for detailed descriptions of various aggregation rules.

Belief aggregation, also called risk aggregation,opinion aggregation or probabilistic opinion pooling, is a process in which different probability distributions, produced by different experts, are combined to yield a single probability distribution.

An expanding approvals rule(EAR) is a rule for multi-winner elections, which allogs agents to express weak ordinal preferences (i.e., ranking with indifferences), and guarantees a form of proportional representation called proportionality for solid coalitions. The family of EAR was presented by Aziz and Lee.

References

  1. ↑ Aziz, Haris; Bogomolnaia, Anna; Moulin, Hervé (2017). "Fair mixing: the case of dichotomous preferences". arXiv: 1712.02542 [cs.GT].
  2. ↑ Haris Aziz, Barton E. Lee and Nimrod Talmon (2017). "Proportionally Representative Participatory Budgeting: Axioms and Algorithms" (PDF). Proc. of the 17th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2018). arXiv: 1711.08226 . Bibcode:2017arXiv171108226A.
  3. ↑ Skowron, Piotr; Slinko, Arkadii; Szufa, Stanisław; Talmon, Nimrod (2020). "Participatory Budgeting with Cumulative Votes". arXiv: 2009.02690 [cs.MA].
  4. ↑ Ashish Goel; Anilesh K. Krishnaswamy; Sukolsak Sakshuwong; Tanja Aitamurto (2016). "Knapsack Voting: Voting mechanisms for Participatory Budgeting" (PDF). S2CID   9240674. Archived from the original (PDF) on 2019-03-05.{{cite journal}}: Cite journal requires |journal= (help)
  5. 1 2 Benadè, Gerdus; Nath, Swaprava; Procaccia, Ariel D.; Shah, Nisarg (2021-05-01). "Preference Elicitation for Participatory Budgeting". Management Science. 67 (5): 2813–2827. doi:10.1287/mnsc.2020.3666. ISSN   0025-1909. S2CID   10710371.
  6. ↑ Goel, Ashish; Krishnaswamy, Anilesh K.; Sakshuwong, Sukolsak; Aitamurto, Tanja (2019-07-29). "Knapsack Voting for Participatory Budgeting". ACM Transactions on Economics and Computation. 7 (2): 8:1–8:27. doi: 10.1145/3340230 . ISSN   2167-8375. S2CID   37262721.
  7. ↑ Benade, Itzhak, Shah, Procaccia and Gal (2018). "Efficiency and Usability of Participatory Budgeting Methods" (PDF).{{cite web}}: CS1 maint: multiple names: authors list (link)
  8. ↑ Fairstein, Roy; Benadè, Gerdus; Gal, Kobi (2023). "Participatory Budgeting Design for the Real World". arXiv: 2302.13316 [cs.GT].
  9. ↑ The raw data is available here: https://github.com/rfire01/Participatory-Budgeting-Experiment
  10. ↑ Yang, Joshua C.; Hausladen, Carina I.; Peters, Dominik; Pournaras, Evangelos; Regula Häenggli Fricker; Helbing, Dirk (2023). "Designing Digital Voting Systems for Citizens: Achieving Fairness and Legitimacy in Digital Participatory Budgeting". arXiv: 2310.03501 [cs.HC].
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