Ranked Choice Voting and ‘Structural Democracy’
Since 2019, we’ve pursued a major research theme in structural democracy, meaning the study of voting rules and electoral systems in terms of their properties. For example, ranked choice voting is a reform to move away from first-past-the-post voting that’s being debated around the country– but there’s far too little work that models its effects on representation.
Our work is both theoretical and practical, from building new statistical models of ranking to testing fairness properties across election systems to writing public-facing reports for communities considering a change of election system.
Here is a selection of projects that the lab has been involved in…
Proportionality for ranked voting, in theory and practice
This project brings a statistical modeling toolkit to the questions around ranked choice voting and proportionality. At the same time, it builds a much-needed bridge from computational social choice theory to political science, where degrees of proportionality have been intensely studied for well over a century, and to the work of practitioners in current reform efforts around voting rights and democracy.
Group fairness in multi-winner elections
There is a large literature on “metric voting” – supposing that candidates and voters can be embedded in some common metric space (often the plane, in examples) and that rankings will be in order of proximity. The embedding is thought to correspond to positions on mutually independent issues. In an econ framework, you could then say that the inefficiency, or “distortion,” of a voting rule is how much further the winners are to voters than the optimal choice would have been.
In this short paper, we show that the usual perspectives on fairness – which look at the society overall or at a worst-case group – are flawed measures of fairness, because they fail to capture the perspective of cohesive blocs of voters with similar preferences.
Case studies and white papers
In a sequence of papers and reports from 2020-2022, we build up a toolkit for understanding ranked choice voting in terms of its tendency to deliver proportional outcomes for minority groups.
- Introducing some generative models that incorporate polarization — SSRN (2021)
- key finding: districts can be good or bad for a minority group depending on how they are geographically distributed and who draws the lines, but RCV secures rough proportionality under a wide range of electoral conditions in four places we studied
- What if the House of Representatives were elected by ranked choice nationally? — FRA project and Supplement (2022)
- key finding: it is surprisingly hard to gerrymander multi-member ranked choice districts!
- Massachusetts has the most uniform political geography of any state we know. How could ranked choice improve representation for minority groups? (including Republicans!) — MA report (2024)
- key finding: when people talk about “ranked choice,” it’s important to distinguish between single-member and multi-member forms, because they can behave very differently
- Chicago has a famously dysfunctional city council election system. What if instead of 50 first-past-the-post elections, there were 10 districts electing 5 members each by ranked choice? — Chicago report (2019)
- key finding: a wide range of representational goals can be achieved in a 10-district plan, including holding Chicago’s “community areas” completely intact
Related software
- VoteKit is a Python package developed and maintained by the Lab to help researchers, litigators, and the public assess ranked choice opportunities. It implements the statistical models introduced in the papers above — GitHub repo
- The Computational Social Choice (COMSOC) website keeps a list of other resources, including other Python packages, collections of ranking data, and fair division algorithms — resource page
More case studies
We have a growing list of individual jurisdictions where we’ve done detailed ranked-choice modeling. Here are some not already listed above….
Whole states
Cities, counties, school boards
- Lowell, MA city council — report
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wide-audience reports in English Khmer Spanish Portuguese
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- Portland, OR city council — report
- Oregon school districts — Beaverton report, Hillsboro report, Salem-Keizer report
- Washington county commissions — Chelan County report, Pierce County report
- Washington school districts — Tukwila report, Wenatchee report