[EM] An example of BTR-STV

raphfrk at netscape.net raphfrk at netscape.net
Wed Jun 7 04:33:23 PDT 2006

Anthony O'Neal <thasupasacfitinman at gmail.com> wrote:
>  (This is the election I pulled out of the Wikipedia article for 
> I just didn't feel like making up an election where the results from
> CPO-STV and STV differ right now. If you want to see how
> the results for the CPO-STV and STV results were arrived upon, then
> go to the article)
>(PS, does anyone know what the BTR part of BTR-IRV means?
> Honestly, I can't figure it out, but that's what Warren on 
> calls it. I'm thinking of changing the name to Majority Elimination 
by IRV,
> or ME-IRV, and ME-STV, but if BTR makes more sense...)

It is probably "Bottom Two Runoff" or something similar.

> Now for this election, using the Hagenbach-Bischoff quota of 
votes/seats + 1,
> the amount needed to get elected is 25 votes. So Andrea and Carter 
> immediately declared elected, as their amount of votes exceeds the 

Why not use the Droop quota, that is much fairer?

Otherwise, "vote management" is a viable strategy.  If a party has 44% 
of the vote
and can manage to split the vote evenly between two candidates 22% 
each, then they
both get elected.  If they don't bother with vote management, the more 
candidate will only be able to transfer votes above 25%.  The second 
will only get 19% of the vote which isn't enough for a 2nd seat.  The 
system of
election should not encourage tactical voting if possible, people 
should be
encouraged to vote honestly.

> I believe that the second method, not counting already consumed 
> is the proper method, but this may just be bias since I'm trying to 
paint my
> method out to be simialar to CPO-STV. I have presented both, so if 
> of you know more about the subject feel free to point me in the right 

That seems fair.  It is unreasonable that people who have already
elected a candidate (or will elect a candidate) should have a say in 
who gets

What about something like multiple stages

Stage 1:  standard PR-STV is used to select potential winners.

Stage 2+: BTR-STV is run to select a (potentially) different set of 

Ballots which are held by potential winners from the previous stage or 
 from the current stage who have been deemed elected shall not be 
when determing which of the bottom two should be eliminated (unless 
they are
held by one of the bottom two)

Keep going until 3 stages in sequence result in the same set of 
potential winners
and deem those elected

After a cutoff number of stages, either select the winners of the last 
stage or
the winners of the second last stage as winners by a "coin toss".

I wonder if this diminishes the problem that BTR violates later no 
harm.  Your
lower ranked choices will not be considered unless your current 
is unlikely to get elected.
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