Photo Courtesy Haas School of Business, U.C. Berkeley

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.