[EM] Need IRV examples; voting show

[Adam Tarr]

James Gilmour wrote:

>I don't want to play semantics, but surely if (as you said) "approval ballots
>contain information not present in ranked ballots", the ranked ballots must
>contain less information than the approval ballots?  Or do you mean that they
>contain similar amounts of information, but that it is different?  (That it is
>different is, of course, self-evident.)

I think all Bart's trying to say is that the approval cutoff is not obvious 
on a ranked ballot, and is obvious on an approval ballot.

>I fail to see how the information a ranked ballot will be used in a more 
>haphazard
>(random) way.  No matter how many times ballot papers are recounted under 
>the IRV
>rules I have used for many years, you will always obtain the same result.  So
>there should be nothing haphazard about it.

That's not what he means by haphazard.  What he means is that, because IRV 
only looks at the top-ranked candidate on a ballot at any time, the ability 
of IRV to reflect the majority choice can be erratic at times.

The classic example (on this list anyway) is the "left, middle, right" race 
where middle narrowly loses in the first round despite being every voter's 
first or second choice.  Middle would beat either candidate in a head to 
head race.  In this case that IRV doesn't really manage to "identify the 
one candidate who is most representative of those who vote" (your quote), 
although some IRV advocates will actually try to argue that it does.

>There may be some problem with the rules you've seen for counting IRV 
>ballots, but
>in the rules I've used for many years, it is just impossible for any voter 
>to have
>his or her vote counted for several candidates and so secure more than one 
>vote.
>With IRV, the voter has one vote.  That vote is transferable, but the whole of
>that one vote counts towards the election of only one candidate.  If the 
>voter's
>most preferred candidate ceases to be a candidate, because he or she is 
>excluded,
>then the one vote is transferred to one other candidate and counts exclusively
>towards the election of that one candidate.  I think this demonstrates "one
>person, one vote" throughout the entire process.

Right, but that person's vote, at one time or another in the process, could 
have voted for many candidates, while someone else's vote may have only 
voted for one candidate the whole time.  So, in some sense, "one person, 
one vote" was violated.

OK, so I recognize that that's a silly, spurious argument.  I have lots of 
problems with IRV, but violation of 1P1V is not one of them.  But really, 
is this argument any more spurious than the argument that Approval violates 
1P1V?  Not if you think about it.

When I vote in an IRV election, my vote can be cast for a number of losing 
candidates along the way, but in the end I only get one vote in the 
deciding contest where someone breaks 50%.

When I vote in an approval election, I can cast a vote for any number of 
losing candidates, but I can only get one vote in the deciding contest 
between the two front runners.  (Or I may vote for both of them, which of 
course cancels my vote completely).

Don't you see that this is completely equivalent?  There's no way I can get 
more than one vote that matters toward the actual outcome of the election.

> > With Approval everyone gets exactly one vote per candidate, and the vote
> > may be to "approve" or "not approve."
>
>Yes, but "one vote per candidate" is somewhat different from "one vote per
>elector".

How about, "one vote per winning candidate".  Is that any different?  When 
you think about it that way, approval is the same as IRV or plurality or 
Condorcet.  The only voting system which does seem to violate that 
principle is Borda, which is part of the reason Borda would be such a 
nightmare for public elections.

> > And as has been pointed out, with
> > approval any individual voter can vote in such a way as to cancel out
> > any other voter.
>
>Surely, this feature is not to Approval?

I assume you meant to write "unique to Approval".  The Borda count shares 
this property, so it's not unique to Approval.

-Adam


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