20 June 2023

The rise and rise of Participatory Budgeting (PB) is showing no signs of slowing down. Last week, the City of Boston named Renato Castelo its first-ever Director of its new Office of Participatory Budgeting. In the same week, a vote to increase the city’s PB budget from $2 million to $20 million ended in deadlock – but campaigners are fighting back with calls for $40 million.

Meanwhile, in Europe, some experts have begun calling for an EU-wide PB. This would potentially allow citizens from across the 27 states to help decide how the world’s largest trading block spends a portion of its budget.

Whatever the scale of a PB, the basic format remains the same. In an initial phase, residents propose projects to be allocated a portion of a city or region’s budget. In a second phase, the proposals are put to a public vote. This format is similar to most PBs. But there is one key difference between many of the world’s PBs: the voting method they use. 

Why PB voting methods matter

How ballot papers are completed and counted can make a huge difference to the outcomes of elections. The topic has recently been attracting a lot of attention with regard to national elections and political primaries. It is also a crucial issue for Participatory Budgets. 

The format of PBs means that they come with their own unique set of challenges. For one thing, they usually involve multiple winners. But they also feature projects of widely varying costs, a factor which voters should be encouraged to consider when casting their votes. 

Luckily, digital voting makes implementing complex voting systems easier than ever. This has given cities around the world the freedom to experiment with a whole range of different approaches. Let’s look at some of the most compelling among them. 

A standard voting method for PB: Approval voting

The most tried and tested voting method for PBs. It is like a traditional ballot paper, except rather than placing an X in just one box, the voter is allowed to choose multiple projects. 

PBs usually implement a variety known as k-approval voting – where k stands for the maximum number of projects you can vote for. This is typically between three and five – though Warsaw has previously allowed residents to choose up to 15 district-based and 10 city-wide projects. 

The big advantage of approval voting is that it is simple to understand, and quick to complete. But it also comes with some disadvantages. The biggest is that it doesn’t explicitly require voters to take the cost of the different projects into account. 

If you ask someone to choose their three favourite projects, there’s a good chance they will select three high-impact, high-cost projects to try to maximise the impact of their vote. Yet if the budget is only large enough to implement one of them, this means the other two votes were effectively wasted.

Some PBs get around this problem by splitting the projects into cost categories. They allow voters to choose e.g. one high-cost and three low-cost projects. But there are also more sophisticated ways of tackling this problem…

Knapsack voting

What if instead of choosing a certain number of projects, residents were given an imaginary budget to spend as they see fit? Maybe given the choice, some voters would prefer to opt for five or six smaller projects, whose total cost still comes in lower than one large one. Why not let them? 

That’s the idea behind knapsack voting. Rather than choosing a fixed number of projects, voters can choose as many projects as they like, as long as their combined cost is lower than the PB’s total budget. While this would be difficult to administer with a paper ballot, digital versions are simple and easy to use. 

The great thing about knapsack voting is that it gets residents more involved in the deliberative process. It confronts them with the question: Given budgetary limitations, which range of projects would you choose to implement? This prompts voters to take into account the value for money of the projects. It also gives them insight into how these kinds of decisions typically get made, and encourages them to accept the kind of compromises democratic budgets are all about. 

A brief note on terminology: The term knapsack voting was proposed by a team of Stanford researchers in 2016. While the name was new, the concept was not: A similar method known as “open active voting” has been in use in the “My Neighbourhoods” project in Rekjavik since 2012. And since 2016, Madrid has employed its similar “shopping cart” voting system. 

The method of equal shares

PBs may have been around for a while now, but new PB voting methods are still being developed. The latest to be trialled is the method of equal shares. It was specifically designed to resolve a drawback with knapsack voting. 

A simplified example is enough to make the idea clear. Let’s say that using knapsack voting, 51% of residents vote for 5 projects that are climate-focused, while 49% vote for 5 projects that are community-focused. 

Under knapsack voting, all 5 climate projects would be implemented, and none of the community projects. In other words, 49% of voters would go home empty-handed. 

Under the method of equal shares, in the vote-counting phase, each voter is allocated a fixed proportion of the budget. If only 51% of voters voted for the climate projects, then no more than 51% of the budget will be allocated to them, with 49% being reserved for the community projects. 

This helps to ensure that everyone’s voice gets heard. Think of it as a kind of proportional representation for PBs.

The method of equal shares is a new kid on the block – but it has already been used in Wieliczka, Poland in April 2023. And voting is currently underway using the method in Aarau, Switzerland, with polls closing on 25 June 2023. 

Majority judgement method

Paris is home to one of the world’s largest PBs. In 2022, the city spent an impressive €82 million on implementing projects. Voting for this year’s PB opens in September, when residents will cast their vote using the majority judgement system. 

Majority judgement is a form of cardinal voting. Rather than choosing a range of projects, voters are asked to assess the quality of all of the proposed projects one by one, awarding them a rating somewhere between “excellent” and “unsatisfactory”, or between one and five stars.

The Paris PB switched to this system back in 2021, having previously used the k-approval system, with residents selecting 4 citywide and 4 district projects. Residents can now offer one of four unmistakably French verdicts on the proposed projects: “coup de cœur / j’adore” (love at first sight / I love it) , j’aime bien / c’est interessant” (I quite like it / it’s interesting), “pourquoi pas?” (why not?), or “je ne suis pas convaincu(e)” (I’m not convinced).

According to the Paris PB team, the method offers various advantages. For one, it allows voters to express both positive and negative opinions, meaning they can help “eliminate” projects they would prefer were not implemented. It also prevents strong projects that are nonetheless nobody’s favourite from being eliminated too quickly. 

Like knapsack voting, it has the advantage of requiring a longer process of reflection. It’s worth noting, however, that this can be both a blessing and a curse. On the one hand, it encourages voters to weigh up all of the options, and not to gravitate to the most eye-catching projects. Yet it also demands a far greater time-input than approval voting, which can potentially lead to lower participation rates. 

Making votes in PBs count

This list is by no means exhaustive. And who knows, perhaps even more new and improved methods will emerge in years to come. 

But for the time being, all of the methods above provide a more nuanced alternative than a simple “cross in a box” approach. It’s crucial that residents are satisfied that they have got their opinion across, and that the final results reflect their input in the fairest possible way. After all, that’s what participatory democracy is all about. 

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