[EM] Re to Ben Grant's first post.

David L Wetzell wetzelld at gmail.com
Sun Jun 16 10:09:34 PDT 2013

Hi Ben, I've pushed at EM a minor adjustment to IRV that solves the problem
you posed.
The idea is to require voters to vote for only 3 candidates and then count
the number of times
each candidate is ranked to determine 3 finalists and then use a ranked
vote to determine the winner.
In each of the cases below, assuming the top 3 get ranked, C wd be
eliminated first by virtue of how none of the 40% voters ranked C.
In that case, the second group would consistently rank B as their top
candidate in the second stage and B would consistently win the second and
final stage.

So IRV is easy to tweak to solve your dilemma.

This fix also makes the vote summarizable at the precinct level in a faster
manner and it encourages voters to rank multiple candidates since
will be more likely to make a diff in the first stage to determine the
final three and it's much simpler than Bucklin or other voting rules.


Message: 1
Date: Sat, 15 Jun 2013 23:26:25 -0400
From: "Benjamin Grant" <benn at 4efix.com>
To: <election-methods at lists.electorama.com>
Subject: [EM] Absolutely new here
Message-ID: <004a01ce6a41$4989a8e0$dc9cfaa0$@4efix.com>
Content-Type: text/plain; charset="us-ascii"

I just started trying to wrap my brain around all the ins and outs about
voting methods, and I wanted to check two things with my elders (on this

1)      As far as I can see, the reason IRV has some strange/unusual results
is because it is absolutely critical what order you eliminate candidates. So
an election where Voting Bloc 1 has a 13% share of the ballots and Voting
Bloc 2 has a 16% share of the ballots can utterly flip around using IRV if
VB1 goes up two points and VB2 goes down 2. Because with IRV, the order of
elimination is really the first-most deciding factor in who wins.  For
example, here are three different scenarios:

40%        A             B             D             C

25           C             B             D             A

20           D             B             C             A

15           B             A             C             D

                WINNER: A

(the topline means of course that 40% put candidate A first, B second, D
third, and C last.)

40%        A             B             D             C

25           C             B             D             A

26           D             B             C             A

9              B             A             C             D

                WINNER: D

40%        A             B             D             C

25           C             B             D             A

17           D             B             C             A

18           B             A             C             D

                WINNER: B

A few percent either way on the last line changes *everything*.

This seems to be a flaw with IRV, yes? It is "too sensitive" on small
changes because they can change the order of elimination.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20130616/8fe7bfec/attachment-0003.htm>

More information about the Election-Methods mailing list