Admittedly, there are many phrases in the lexicon of electoral reform that have been used to describe IRV and IRV-like voting systems. The terms preferential voting, single transferable vote, and choice voting are a few examples. Some have also asked how IRV relates to the proportional representation system used by our neighbor, the City of Cambridge. This post hopes to clarify any confusion about what all these terms mean and how they differ (or not) from one another.
Let’s start by understanding the distinction between a “single-seat” and “multi-seat” election. In Somerville, the elections for Mayor, Ward Alderman, and School Committee members are “single-seat”, because each of these offices is held by a single individual. However, the Aldermen At-Large election is “multi-seat”, because it elects multiple candidates (four, in our case) to the same office. Unlike much of the world, nearly all of our elections in the U.S. are single-seat, with at-large city councilors being the most common exception.
The term preferential voting can be used to describe any voting system in which voters rank candidates on the ballot in order of preference. There are many preferential voting systems, some of which can only be applied to single-seat elections, and others which can be used to elect any number of candidates. Although all preferential voting systems are similar to one another in the look of the ballot and the voting instructions, they differ in how the votes are tabulated and can therefore disagree as to the winner of a given election.
By far the most common type of preferential voting system in the world is the Single Transferable Vote (STV). STV is applicable to both single- and multi-seat elections, and it is promoted by the world’s leading electoral reform organizations, including the Electoral Reform Society in the UK and FairVote here in the U.S. STV is held in high regard by academics and reformers alike.
When STV is applied to a single-seat election, it is commonly known in the U.S. as Instant Runoff Voting, but that name is far from universal. Some U.S. cities that use IRV call it ranked choice voting. Elsewhere you may hear it called the Alternative Vote or the Hare method. Other places simply know it as “preferential voting” — an ambiguous phrase considering the variety of systems that involve ranking candidates in preference order.
When STV is used for multi-seat election, it is commonly known in the U.S. as Choice Voting. The City of Cambridge uses Choice Voting for all its City Council and School Committee elections. Conceptually, you can think of Choice Voting as a version of IRV that has been amended to elect multiple candidates at once.
The goal of “Somerville for IRV” is to enact the Single Transferable Vote for all municipal elections in Somerville. We want to use IRV for the Mayor, Ward Alderman, and School Committee elections, and Choice Voting for the Alderman at Large election. For the purposes of simplicity, we are proposing the entire reform under the more familiar phrase “Instant Runoff Voting”.
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