What Do They Think of RCV in Bah Hahba?

June 14, 2018 at 12:45 pm 2 comments

The Society of Actuaries does it.

Seventy-five percent of Great Britain — Scotland, Northern Ireland, and the United Kingdom — does it. (Fucking Wales.)

The Academy of Motion Picture Arts and Sciences does it.

And now Maine, the first state to implement a one-to-one laptop program for all students, does it, too.

The “it” is ranked-choice voting, a method that allows voters to rank the candidates in their order of preference. When used to elect a single candidate, ranked-choice voting helps to select a winner that reflects the support of a majority of voters.

Many cities and towns already use ranked-choice voting to elect mayors and members of council. But Maine is the first state to use it for state and federal elections.

Many people, including Jennifer Lawrence, support ranked-choice voting. (That should mean something, right? After all, she’s the only person born in the 1990’s who’s won as Oscar. So far, anyway. Maybe she supports ranked-choice voting because the Academy used ranked-choice voting to award her an Oscar? Who knows.)

This video gives a very simple example of how ranked-choice voting works.

But maybe there’s a better example. Imagine that a book club is trying to decide which book they should read next, and rather than just voting for their top choice, the group instead ranks each of three books:

  • Math Jokes 4 Mathy Folks (MJ4MF)
  • The Grapes of Math (GM)
  • Riot at the Calc Exam, and Other Mathematically Bent Stories (RCE)

The voting proceeds as follows:

Order Number of Votes
MJ4MF / Grapes / Riot 4
MJ4MF / Riot / Grapes 5
Grapes / MJ4MF / Riot
Grapes / Riot / MJ4MF
Riot / MJ4MF / Grapes
Riot / Grapes / MJ4MF

First, consider only the first-place votes, and determine if any candidate received a majority. In this case, none of them received more than half of the first-place votes: MJ4MF received 9 first-place votes, Grapes received 8, and Riot received 3.

Since no one won, the candidate with the fewest first-place votes is eliminated. Sorry, Colin Adams; we’ll have to say good-bye to Riot at the Calc Exam.

Now, the voters who had their first choice eliminated will have their votes counted for their second choice instead. So, 2 additional votes go to MJ4MF, while 1 vote goes to Grapes.

This means that MJ4MF, with 9 + 2 = 11 votes, is the winner, since Grapes received only 8 + 1 = 9 votes in the second round. Sorry, Greg Tang; you should’ve chosen a less worthy adversary.

C’mon, now… you didn’t really think MJ4MF was gonna lose, did ya?

On Tuesday, voters in Maine used ranked-choice voting to decide several political races, but they also got to vote on whether to use ranked-choice voting in future elections. Because ranked-choice voting takes time to tabulate, two of Tuesday’s contests were still undecided as of Thursday morning. So, voters literally were asked to decide if they should keep or reject a system that they had never seen used in an election. Doesn’t that seem just a bit odd?

You know what else is odd? Numbers that aren’t divisible by 2.

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Fortune Bank Teller How Would You Answer These Questions?

2 Comments Add your own

  • 1. Xander  |  June 15, 2018 at 11:24 am

    Borda count for the win! But no mention of Arrow’s Impossibility Theorem? Aww… 😦

    • 2. venneblock  |  June 15, 2018 at 12:16 pm

      Totally with you! But it seems that government is a LITTLE scared of RCV and a LOT scared of Borda! I suspect most politicians don’t understand it, and they fear trying to explain it to their constituents. And perhaps rightfully so — see Indiana Bill 246 from 1897, https://en.wikipedia.org/wiki/Indiana_Pi_Bill.

      But maybe I shouldn’t throw stones… might be the same fear that prevented me from mentioning Arrow.


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About MJ4MF

The Math Jokes 4 Mathy Folks blog is an online extension to the book Math Jokes 4 Mathy Folks. The blog contains jokes submitted by readers, new jokes discovered by the author, details about speaking appearances and workshops, and other random bits of information that might be interesting to the strange folks who like math jokes.

MJ4MF (offline version)

Math Jokes 4 Mathy Folks is available from Amazon, Borders, Barnes & Noble, NCTM, Robert D. Reed Publishers, and other purveyors of exceptional literature.

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