[EM] MAV on electowiki

Jameson Quinn jameson.quinn at gmail.com
Thu Jun 27 07:37:01 PDT 2013

2013/6/26 Chris Benham <cbenhamau at yahoo.com.au>
> Jameson,
> I don't like this version at all. These methods all have the problem that
the voters have a strong incentive to just submit approval ballots, i.e.
only use the top and bottom grades.

You are right... if they believe that all other voters will act the same
way. But if experience has shown that there are enough "honest" voters so
that winning medians¹ tend to be in a given range, then it is safe to vote
expressively outside that range.

¹ Actually, as long as your vote for your preferred frontrunner is above
the second-place median, and your vote for your less-preferred frontrunner
is below the first-place median, your vote is strategically optimal.
> Your suggested way of determining a winner among candidates who first get
a majority in the same round only makes that incentive a bit stronger still.

I don't see it. The MAV completion method is as close to later-no-harm as
is possible in a Bucklin system; which tends to balance out the
later-no-help. I think you're the one who's pointed out before that passing
one and failing the other is usually worse than failing both; by the same
token, if one is passed by all Bucklin systems, then the Bucklin system
which fails the other by the least is the best.

> I agree with a Mike Ossipoff suggestion, that we elect the member of that
set of candidates with the most above-bottom votes.

That completion is fine. My larger point is that it's silly to fight about
these issues. We should settle on one Bucklin proposal and stick to it. I
currently believe that MAV is most viable in that sense, but I'd be happy
if you got enough support for the Ossipoff suggestion to convince me

> Also, given the strong truncation incentive, I think 5 grades is one too
many. In my opinion 4 grades would be adequately expressive.

I personally slightly prefer 5 grades. It increases the probability that a
voter who wants to be strategic and confidently knows the expected range of
possible winning (and second-place) medians, will have room to make
purely-expressive distinctions at the top and/or bottom of the ballot. In
other words, if you know that the winner always gets a C, then it is
strategically safe to make honest distinctions between A/B or between D/F.

But that's a slight preference. If demonstrate that your position has more
support among the active posters here, I'd join with you for the sake of

> My favourite Bucklin-like method is "Irrelevant-Ballot Independent
Fallback-Approval" (aka IBFA) that I introduced in May 2010.

I think that's a great method, but I would classify it as "improved
Condorcet" rather than "Bucklin-like". I think it would be productive to do
the same work for the improved Condorcet systems that I'm trying to do with
Bucklin: that is, to settle on a single simple proposal that people can
agree is among the better options (even if they can't agree it's best), and
find a simple descriptive name for that proposal. I expect IBIFA would be a
strong contender in that process. It's possible that in the future, Bucklin
and Improved Condorcet advocates could agree to join forces, but I suspect
it's premature for that at the moment.

If you disagree with the above, I'd be interested to hear how you see it.

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