[EM] "good method" ? was "IRV ballot pile count (proof of closed form)"

[Kathy Dopp]

> Date: Sat, 13 Feb 2010 17:24:15 -0500
> From: Abd ul-Rahman Lomax <abd at lomaxdesign.com>
> To: kathy.dopp at gmail.com,election-methods at lists.electorama.com
> Subject: Re: [EM] "good method" ? , was "IRV ballot pile count (proof
>        of closed       form)"
> Message-ID: <20100213223844.C90878DB009D at zapata.dreamhost.com>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> At 03:29 PM 2/13/2010, Kathy Dopp wrote:
>> > From: Chris Benham <cbenhamau at yahoo.com.au>
>> > 35:A
>> > 32:B>C
>> > 33:C,
>> >
>> > by which I mean
>> >
>> > 35:A>B=C
>> > 32:B>C>A
>> > 33:C>A=B.
>
> Kathy doesn't seem to recognize this, or maybe she does, but the two
> statements are equivalent. By not ranking B and C, the voter
> equal-ranks them bottom. That is the exact effect of the vote.

I seem to be one of the few people on this list who recognizes that I
don't read voters' minds and cannot convert one vote-type to another
for voters.

For example, in the above example, by:

>> > 35:A

Some voters if they chose to rank further might have meant:

A>B=C
or they might have wanted:

A>C>B
or
A>B>C

and the same for
>> > 33:C

We disagree on whether or not you and other members' interpretations
of how voters would alter their votes are self-evident or not.  Poll
100 voters, I doubt that the mind-reading abilities of persons on this
list will hold uniformly for all of the voters you poll.

We may disagree with the counting method that is applied when
>> > 35:A
>> > 32:B>C
>> > 33:C

occurs, but it seems very clear that the Condorcet winner in this case
is C, as you seem to agree with me in this case.

However, that is not the case when we make assumptions for how the
voters would change their votes (see below)


>
>>I agree with Chris (below), If you require every winner to "have a
>>majority *over*" ever other candidate, then there is no system that
>>would give you any winners.  Clearly above, C has 65 votes and B only
>>has 35 votes, at least in scenario #1 above.
>
> Actually, with the votes above, C has a plurality over every other candidate:
> A:B 35:32, A
> B:C 32:33, C
> C:A 65:35, C
>
> C wins every pairwise election, C is the Condorcet winner. "Condorcet

Yes. As I think I said in my first email. But A is the winner if you
alter the votes as per the email I was responding to.

> winner" does not at all require a majority in every pairwise
> election, and, in fact, that was part of my point. It's possible that
> the Condorcet winner only has a plurality in all of them. But in this
> particular case, a majority of voters have chosen to cast a vote that
> can be read as a vote for the Condorcet winner. All we have to do is
> take the B>C votes as such. They are clearly votes against A. So
> two-thirds of the voters have voted against A. A's out.
>
> 65 voters have voted for C, but only 35 have voted for B.
>
> "Vote for" means "cast a vote that can be used to elect."
>
>>Guessing as to what voters really mean, by assuming scenario #2 from
>>scenario #1 -- you may have read the minds of all those voters who you
>>believe all think exactly alike in each category, incorrectly.
>>However, in scenario #2, I think A is the correct winner.
>
> They are the same scenario, in fact. I think you misread this, Kathy.
> Equal-bottom is the same as not expressing the candidate's rank at all.
>
>>I think election methods enthusiasts too often think they can read
>>voters' minds and translate votes between between two different
>>scenarios for voters.
>
> Perhaps you mean that the B=C part of A>B=C means that the voter
> really did mean to actually equate them. Okay, let's look again. I
> assumed in a previous mail, Range utilities of
>
> 35: A, 3 / B, 1 / C, 0
> 32: B, 3 / C, 2 / A, 0
> 33: C, 3 / A, 1 / B, 0

In this case, A is the Condorcet winner 68 persons preferring A over
B, 67 preferring B over A, 65 preferring C over A, 67 preferring B
over C, etc. not C as in your first, not-equivalent, example.

So it appears that Range voting does not find the Condorcet winner in this case.

Kathy

>
> Range totals:
>
> A: 138
> B: 131
> C: 163
>
> This allows the A voters to still have a preference between B and
> see, but at a lower level. If, in fact, they had no preference, the
> result becomes simply a lower sum of ratings for B. And if the C
> votes really did mean that A and B were equal, the result becomes
> fewer votes for A.
>
> C still wins.
>
> If the method were Bucklin, then, again, C would win, easily, with
> 65/100 voters approving of C, if the votes were as writ.
>
> With Bucklin, would more of the B voters truncate? Maybe. Maybe not.
> Depends, doesn't it?
>
> It depends on how strong their preferences are. If it's Bucklin and
> everyone truncates, A wins, by a narrow margin. Same as with
> Plurality. But if a majority is required, it would go to a runoff.
>
> Do we know, then, who would win? No, we do not. We do not have enough
> information! If the B votes really do show a higher approval of B
> voters for C, then C might win, but in that case some of them would
> probably also approve of C in Bucklin.... and then C could still win
> in the first round.
>
> The scenario I worry about here is that B is really the Condorcet
> winner, and the Range winner, and the B voters were merely more
> willing to disclose lower preferences. IRV will choose A and C for
> the instant runoff, and top-two runoff for a real runoff, which is
> fine, except for that contingency.
>
> I do believe that Bucklin would handle this well, in general. Some
> voters will add lower preferences, enough to show, even if there is
> majority failure requiring a runoff, what the best two candidates
> would be for the runoff. Again, if write-ins are allowed in the
> runoff, and the wrong two candidates get there, and there is real
> preference strength behind that error, the voters can fix it.
>
> They will be in a better position to do so if the ballot is actually
> a range ballot, they will have a better idea of the chances of a
> write-in campaign in the runoff.
>
>
>
Kathy Dopp
http://electionmathematics.org
Town of Colonie, NY 12304
"One of the best ways to keep any conversation civil is to support the
discussion with true facts."

Realities Mar Instant Runoff Voting
http://electionmathematics.org/ucvAnalysis/US/RCV-IRV/InstantRunoffVotingFlaws.pdf

Voters Have Reason to Worry
http://utahcountvotes.org/UT/UtahCountVotes-ThadHall-Response.pdf

Checking election outcome accuracy
http://electionmathematics.org/em-audits/US/PEAuditSamplingMethods.pdf