The online experiment on Qualtrics consists of two voting rounds. It is an incentivised experiment, that is, participants receive money
depending on their choices in their final round of voting.
First, the participants are introduced to a vignette : They live in a virtual city with 3 districts (Nord, Süd, West) with different proportion of the city population (10%, 30%, 60%) and they are asked to cast their vote in a participatory budgeting (PB) program. In order to understand how being a part of the minority or majority affects voters’ perception of the outcome, the participants are randomly assigned to one of the following four settings with different population distribution. The difference in demographics is also reflected in the voting aggregation outcome in the later stage.
Participants are then shown a table with realised bundles of a simulated outcome of the PB program, with projects selected using the two different aggregation methods with 200 simulated voters. The number of votes on a certain project roughly reflects the population of the respective district. The participants are then asked to compare the two outcome using a simple Greedy outcome, selecting projects based on number of votes, and Method of Equal Shares, allocating budget to projects proportional to number of voters, and rate them in terms of (1) legitimacy, (2) how easy they found the voting task, and (3) how well the assigned input format captured their preferences.
In the second vote, participants proceed to the more realistic PB voting with project categories and different costs on top of the district of the projects. The projects are extracted from the Zurich 2021 city PB project with some level of abstraction and alteration. In this vote, participants are asked to pick the district in the city they identify with the most, and they would act as the residents of the districts in this realistic PB vote. As the participants are all university students in Zurich, it is assumed that they have a certain level of connection or understanding of the city.
They are asked to cast their vote in 6 different commonly used voting input methods in PB: (1) Select any number of projects (2) Select 5 project (3) Distribute 5 points (4) Distribute 10 points (5) Select 5 and rank (6) Distribute 10 points for 5 projects. Then, they can rate these input methods in terms of ease of use and expressiveness.
The participants are shown different random simulated voting results with outcomes calculated using (1) Greedy Method (2) Method of Equal Shares. They are then to assess the different outcomes and rate outcomes in terms of satisfaction, fairness, and the trustworthiness of the methods. Then, the participants are randomly put into 3 different groups with different kind of explanations (mechanism explanation, the distribution of individual budget won, & the distribution of budget according to district and categories). The participants are asked to rate fairness and trustworthiness again. They are shown the budget distribution of the two outcomes and they have to choose which distribution they would rather be a random voter. Finally, the participants will be asked to vote for their preferred voting input and aggregation method. The most supported voting input method and voting aggregation will be used to calculate their final compensation pay-off for the experiment.