[EM] Bucklin/IRV hybrid? Motivated by MSV strategy

Michael Ossipoff email9648742 at gmail.com
Sun Oct 30 14:18:15 PDT 2016


On Sat, Oct 29, 2016 at 11:16 AM, Jameson Quinn <jameson.quinn at gmail.com>

> ....Here's my "ideal characteristics" for a political single-winner
> election system, more or less in descending order of importance:
>    1. FBC
Yes, I consider FBC to be #!.

>    1.
>    2. Handles center squeeze (ie, some form of weakened Condorcet
>    guarantee that's compatible with FBC)
> But maybe the goal of electing the CWs unnecessarily complicates votiing.
Maybe someday, there won't be a bottom set, for most voters, and, with
honest elections & honest, open media, it will be clear who's the CWs. But
now, Approval's best strategy doesn't require that. Brams pointed out that
Approval's results can be better than the CWs.

But, when it's desirable to elect the CWs, and it isn't obvious who's the
CWs, then the wv methods, and methods with wv-like strategy (such as MMPO),
are the methods that make it easiest to protect the CWs.

Also, it should be noted that you can't be sure how often there will be a
CWs, under different and better conditions.

>    1.
>    2. Relatively simple to explain
Approval & Score are easy to explain. I've had conversations in which only
Approval & Score were accepted as being plain & un-elaborate enough to be

You know that SARA & XA are complicated and not easy to explain. I've tried
explaining them.


"The winner is the candidate who has fewest people voting someone else over

{...some same other candidate)

>    1.
>    2. Minimal strategic burden
We often hear it said that Approval has a large strategic burden, but, for
most people, with our current candidate-lineup, there's nothing difficult
about it: Approve (only) the progressive candidates. That's optimal for
most people.

And if the time comes when, for most people, there isn't a bottom-set, then
that will be a happy circumstance, in which it doesn't matter terribly
anyway, which candidate wins.

In such conditions, with honest elections and honest, open media, it will
likely be pretty obvious who's the CWs, and, in the absence of
tep-set/bottom-set, the best strategy will be to just approve down to the

And, if there were no bottom-set, and if it happened that it _wasn't_ clear
who the CWs was, and it was 0-info, then it would just be a matter of
approving down to the expected winning merit-level. Maybe, under those
conditions, that would be the candidate-mean.  Or maybe (as now)  the
estimated mean merit of what voters want (which can be estimated by the
candidates' merit-midrange, if the election is 1D.  ....but it might not
remain 1D under different and better conditions).

..but I repeat that, with only your former top-set remaining as winnable
candidates, it won't make as much difference which one wins anyway.

People often consider Approval voting more difficult than it is.

>    1. Summable (ideally O(N), no worse than O(N²) in practice, though I
>    might accept some special pleading for the use of prior polling to reduce
>    to O(N²).)
>    2. Handles CD, or at least, CD offensive strategies don't in practice
>    mess up the center squeeze properties.
MMPO meets Weak CD.

>    1.
>    2. Some arguable track record
Of course at EM we discuss two completely separate and different method
proposal choices:

1. Proposals to electorates who have only had Plurality.

2. Later proposals to replace one better voting system with another.

If we're talking about #1, then there are only a few to choose from:

Approval, Score, and Bucklin.

I suggest that all 3 of those should be offered to initiative-proposal
committees, and that the public should be polled, or consulted in
"focus-groups", regarding which of those 3 methods they'd  accept

For #2, it really takes something with a lot of valuable &
otherwise-unobtainable properties, to justify replacing Approval, Score or
Bucklin with it.

I suggest that only Plain MMPO qualifies.

>    1.
>  Approval does well on 1,3,4, and 6, is OK on 2, and bad on 4 and 5.

No. Contrary to what we so often hear, Approval doesn't have a high
strategic burden, as I discussed above.

Other than MMPO's CD, improvements over Approval by more complicated
methods are illusory.

And your standard #5 was summability and count-complexity. Approval is
precinct-summable, and its count is the easiest and least
computation-intensive, among voting-systems.

Michael Ossipoff
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