Thursday, December 10, 2009

An Instant Runoff Voting Majority is not what you think

One of the claims in favor of instant runoff voting is that it provides a majority winner. That is true only if you redefine what "majority winner" means.

In San Francisco,"majority" is of the "continuing" ballots, not a majority of all ballots:

"If no candidate receives a majority of votes from the continuing ballots after a candidate has been eliminated and his or her votes have been transferred to the next-ranked candidate, the continuing candidate with the fewest votes from the continuing ballots shall be eliminated. All votes cast for that candidate shall be transferred to the next-ranked continuing candidate on each voter's ballot. This process of eliminating candidates and transferring their votes to the next-ranked continuing candidates shall be repeated until a candidate receives a majority of the votes from the continuing ballots." SEC. 13.102. - INSTANT RUNOFF ELECTIONS.(D) go to this link and type in the SEC. 13.102 in search box. Amended in March 2002.

In other words, the majority consists of the votes left after others are eliminated. The elimination of ballots and the exhaustion of ballots (the point a ballot does not have choices marked) is part of the reason that in many instant runoff voting elections often suffer majority failure.

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New: Instant Runoff Voting majority failure, plurality results in the US

Over at Instant Runoff Voting facts vs Fiction we have updated our page about IRV's pattern of plurality results and frequent majority failure in US locales.

Additions include the majority failure in Cary, North Carolina's 2007 instant runoff voting election, and an Nov 2009 update on San Francisco's election data, including San Francisco elections held by IRV (instant runoff) and ordinary top-2-runoff (T2R) by Warren D. Smith.

If your goal is to end plurality elections, or ensure a majority result, then instant runoff voting is the wrong election method to adopt. If you want to learn more about election methods, there is an excellent discussion group hosted by the Range Voting folks.

Learn more about instant runoff voting's majority failure and plurality results in actual elections in the United States - here.

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