Fairness in Action— Re-weighted Range Voting and the Berkeley City Council
Berkeley had a problem. Cars coming off the I-80/580 interchange were overwhelming a narrow residential street, causing delays and accidents. A citizen petitioned the City Council to create a 4 way stop at Gilman St and Peralta Avenue. This was approved by the council, referred to the City staff, and then languished. The city was overwhelmed with requests from the council and constituents and requested that the council prioritize their concerns.
The Berkeley City Council is made of 8 Districts and the Mayor. Each, except the mayor, has concerns within their district, along with the city-wide concerns. Berkeley was faced with the question of how to prioritize the work for the city government while being fair to each district.
A council member reached out to the Center for Election Science requesting their recommendations. The method needed to be easy to use for the council members, output a ranked priority for each referral and be fair so that a majority of districts did not dominate the ranking system over a minority of districts. To make a voting system fair, you need to make it proportional. Proportional Representation gets deep into the math quickly, but the easiest way of looking at it is when a district gets its concerns met, it should take a step back and give favor to another district so it can get its concerns met.
With these considerations in mind, Berkeley implemented Re-weighted Range Voting (RRV). Council members vote 0–5 stars on each item. The item with the highest score gets first place. But something interesting happens for the remaining items — this is where weighting comes in. District voting power boosted in proportion to how little support they gave to previous referrals. A council member who gave the first referral zero stars has twice the voting power as a council member who gave it five stars. For intermediate scores, the effect lies between those limits. The table is re-calculated without the first place item, then the item with the highest score is selected for second place — and so on. But rather than getting bogged down in the math, let’s look at the results.
Above is the outcome of the Berkeley 2019 Referral Prioritization process using Re-Weighted Range Voting. Let’s see if Re-weighted Range Voting did what we said it would do.
How did weighting change the rankings? We can take the weighted rankings, and then see the difference from the unweighted rankings to see what changed.
Wow! The Install 4-Way Stop at Gilman Street and Peralta Avenue referral moved up 14 ranks due to weighting. Why? It had widespread but minor support from the council members, but the weighting helped increase the value of District 1 who only gave 27 stars to the whole ballot, but a whopping 11% of their vote to that issue. Re-weighted Range Voting enables and encourages council members to support items specific to their district without fear of being lost in the shuffle.
Let’s look at a different scenario. During the most recent council meeting allegations were raised of Re-weighted Range Voting being vulnerable to a “bullet voting” strategy. District 8 chose to spend 100% of their vote share on the Missing Middle Housing Report. The referral moved from 6th place to 2nd place due to re-weighting. The referral had widespread support from the council, or it would not be ranked 6th when unweighted, but District 8’s demonstration of concern allowed it to move incrementally higher. The referral’s high popularity meant that District 8 could have given 58 other referrals five-star ratings without changing the ranking of the housing report. Re-weighted Range Voting encourages voters to contribute their honest feelings on issues. There is little advantage to bullet voting on an item unless that represents your true interests — and sometimes that happens!
One of the other interesting things I found in the analysis of this data set was that there’s a large difference over how much each district will vote. Both the Mayor and District 3 had opinions on most items. District 3 gave ratings on 94.12% of items and gave only three items zeros stars!
It’s important to note that voting for every item does not mean that the district was voting unwisely. Voting for all items but one gives the same relative impact to the weighting as voting for no items except one. Council members benefit from voting with nuance.
This system also allows us to dig deeper into the concerns of individual council members. Let’s pick on the Mayor this time. Here are the Mayor’s prioritized concerns.
Pretty neat, right?
There was a discussion at the most recent council meeting on whether rating should be done by department or not. It’s important for the city to weigh all issues against each other or a coalition could get first place for each individual department before the weighting effect can take hold. Let’s see the Berkeley RRV process from the City Staff’s perspective.
Last week I testified in support of Re-weighted range voting before the City Council. Re-weighted range voting succeeds at its goal of creating a fair and inclusive way for council members to prioritize referrals to the city staff. While the reweighting formula may feel complicated, it’s the results that matter, and RRV delivers.
I’m the Chair of the Board for the Center for Election Science. We are a nationally-based, nonpartisan, 501(c)3 nonprofit dedicated to creating a better world through studying and advancing smarter voting methods. We supported a campaign to bring Approval Voting to Fargo, North Dakota in 2018, and are supporting the campaign to bring Approval Voting to St. Louis, Missouri.
If the above article was interesting to you, I encourage you to subscribe to our newsletter, or better yet, donate to the cause. If you’re interested in bringing RRV, or any other voting method to your city, reach out to us via contact@electionscience.org.
