[EM] Why I prefer ranked-choice voting to approval voting

[Michael Ossipoff]

(Replying farther down--I don't have a way to delete text.)

On Oct 15, 2016 11:49 AM, "robert bristow-johnson" <rbj at audioimagination.com>
wrote:
>
>
>
> ---------------------------- Original Message ----------------------------
> Subject: Re: [EM] Why I prefer ranked-choice voting to approval voting
> From: "Michael Ossipoff" <email9648742 at gmail.com>
> Date: Sat, October 15, 2016 2:32 pm
> To: "Jeff O'Neill" <jeff.oneill at opavote.com>
> election-methods at electorama.com
> --------------------------------------------------------------------------
>
>
> > Jeff:
> >
> > My reply was mostly to your justification of your lesser-evil voting.
> >
> > As for IRV, it can be said more simply:
> >
> > IRV was repealed in Burlington because it violated majority wishes. The
> > Democrat it eliminated was someone who was majority-preferred to
everyone
> > else.
> >
> > A majority consisting of Democrats & Republicans wanted the Democrat
> > instead of the Progressive.
> >

> > That's what the Republicans thought that they were ensuring when they
> > ranked the Democrat in 2nd place:
> >
>

(You wrote) :

> which essentially punished the GOP Prog-haters for voting sincerely.
 despite the (false) promise that they could vote for their favorite
candidate without fear of helping elect their least favorite candidate.

(Endquote)

Exactly.

>
> ...
>
> >

(I'd said) :

> > No voting-system can guarantee that the CWs will always win.

(You wrote) :

> well, if there **is** a CW, any Condorcet method will guarantee that the
CW wins.

(endquote)

Yes, a _voted_ CW (CWv) always wins in Condorcet.

But I'm talking about a _sincere_  CW (CWs).

A sincere  CW, a CWs, is a candidate who'd be CWv under sincere voting.

...a candidate who, compared to each of the other candidate, is preferred
to hir by more people than vice-versa.
>

(You wrote) :

> all of this differentiation between sincere CW and just CW is really too
difficult because we cannot open people's cranium and peer inside to see
what their sincere vote is.

(endquote)

"CW" is used with 2 completely different meanings.

Sometimes, by  CW, people refer to a CWv...& sometimes to the CWs.

It's necessary to distinguish between those 2 meanings, so I use CWs & CWv.

(You wrote) :

i think the only reasonable assumption is that, with sufficient *credible*
assurance (that tactical voting will not help their political interest any
more than sincere voting) that all ballots are sincerely marked.

(endquote)

With most pairwise-count methods, that assurance definitely isn't there.

Say there are 3 candidates: Favorite, Middle, & Worst. W, M, & F.

The Worst voters do the offensive strategy. Middle is the CWs.

By themselves, the letters W, M, & F represent the faction-sizes.

For example, with margins Condorcet, if M's voters rank W 2nd, truncation
by W's voters takes the win away from the CWs if:

1. W > 2M

and

2. F > (M+W)/2

With winning-votes Condorcet, that truncation couldn't possibly succeed. M
wins.

With margins:

If the W voters bury M, then, even if all of M's voters plump,  the burial
takes away M's win and give it to W if:

1. W > M

and

2. W > M/2 + F

With winning-votes Condorcet, if the M voters plump, then burial of M by
W's voters reliably elects F.

(I'd said) :

>
> > But the better methods, like Approval, Score & Bucklin, gjve hir a
better
> > chance than IRV did in Burlington.
>

(You wrote) :

of course, a Condorcet method will do better than any of those.  why bother
with something non-Condorcet if the target is electing the CW?  i don't get
it.

(endquote)

wv RP vs Bucklin:

Both meet MMC, and so if you're majority-favored, then you have the luxury
of being assured of electing from your top-set, merely by you and your
mutual majority ranking sincerely. ...the luxury of being able to choose
among your top-set, assured of electing one of them. ( ...but equal top
ranking , when it departs from sincerity, can violate MMC's premise and
make it inapplicable.)

With both methods, the CWs's voters can protect hir win by plumping. In
Bucklin, it would additionally be necessary for other voters to not rank
past the CWs.

The difference in WV is that, if the threat of defensive plumping has
deterred burial, then a failure to plump is harmless.

The problem with wv (and all Condorcet methods) is the possibility of the
"perpetual burial fiasco":

If the CWs is in your bottom-set, then, by the definitions of
the top & bottom sets, you don't much care which bottom-set candidate wins,
as long as you try to make the winner come from your top-set.

So you aren't deterred from burying a CWs if s/he's in your bottom-set.

So, burial against the CWs could happen all the time, with the result that
the CWs never wins.

The word "cluster-f*ck" suggests itself.

Bucklin is less deluxe, but it's more solid & reliable. And therefore more
proposable.

What about Bucklin vs Approval?:

Not a lot of difference.

Of course Bucklin is stepwise Approval.

Difference:

Bucklin meets MMC, and so you get the above mentioned luxury if you're
majority-favored.

Problem: Only some voters are majority-favored.

1. Often you might not have information to be sure that you are.

2. A benefit for only some isn't so appealing. That lessens its democratic
Importance.

Additional problem:

I'd like to be able to vote equal top ranking in Bucklin, especially if I'm
not majority-favored (MF).

...and seriously gullible & cowardly overcompromisers, like the ones who
are going to vote for Hillary, badly need an equal top-ranking option.

...but the use of it can spoil Bucklin's MMC.

Oops, there goes the advantage.

So wv beats margins, wv's advantage over Bucklin is at least a little in
doubt, and so is Bucklin's advantage over Approval.

The advantage of the rank methods over Approval is questionable.

(You wrote) :

> and direct comparisons cannot be made.  Approval collects too little data
compared to a Ranked Ballot and Score forces the voter to concoct and yield
too much data.  it can only be compared if the ballot format is the same.
 so different RCV methods can be direct compared.  but comparing methods
with different ballots requires assumptions to be made.

(endquote)

No, they can be compared strategically.

...and Uformation-gathering isn't the complete goal.

(Replying farther down) :

>
> > IRV gave the win elsewhere in a way that the people in Burlington
rightly
> > perceived as arbitrary.
>
> not "arbitrary" but incorrect.
>
>
> > For one thing, Approval, Score, & Bucklin allow the CWs's preferrers a
> > better chance to protect hir win, to not give it away.
>
> and Ranked Pairs of Schulze allow an even better chance.

(endquote)

Sure if the perpetual burial fiasco doesn't happen, and if it's
winning-votes instead of margjns.

Margins' protection of the CWs isn't as good as that of Bucklin.

In Bucklin, hir voters can protect hir by defensive plumping.  ...but not
in margins Condorcet.

Michael Ossipoff
>
>
> --
>
> r b-j                  rbj at audioimagination.com
>
> "Imagination is more important than knowledge."
>
>
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