[EM] Manipulability stats for (some) poll methods

[Closed Limelike Curves]

Chris—here in the United States, pushover is well-known and frequently
used, in the context of partisan primaries. We call it "raiding".

Usually it's hard to notice. I suspect the same is true in Australia. The
only difference is here in the United States we manage to notice it from
time to time, because what happens is candidates will run big advertisement
operations that aim to promote an extreme candidate in a primary and give
an easy win. I can't prove the same thing happens with voters, but I'm not
sure how you *would *prove that.

I suspect Australia doesn't have any examples of turkey-raising because it
only has two major parties in its IRV seats, at which point the strategy is
pointless.

On Sun, Apr 28, 2024 at 4:14 PM Chris Benham <cbenhamau at yahoo.com.au> wrote:

> Michael—you're right that it means favorite-burial (cutting the "head" off
> a ballot). The term is quite old, though (older than "favorite betrayal"
> or "favorite burial" I believe)
> <https://www.cambridge.org/core/product/identifier/S0003055400194481/type/journal_article>
> .
>
>
> I don't like either term.  For me, "burial" refers to something a voter
> does to a candidate in the hope that will cause that candidate to lose to a
> candidate the voter prefers, and not just to any insincere down-ranking.
> So "favorite-burial" is  an oxymoron that Mike O. likes to use.
>
> "Favorite Betrayal" meaning to insincerely down-rank one's favourite, is
> ok, but that could either be Compromise strategy (insincerely up-ranking X
> to decrease the chance that X will lose to a candidate you like less) or
> Push-over (insincerely up-ranking X to increase the chance that X will lose
> to say F that you like better, instead of F losing to some Y that you like
> less).
>
> An attempt was made to standardise the terminology here quite a while ago:
>
> http://condorcet.org/emr/defn.shtml
>
> *burying*
> Insincerely ranking an alternative lower in the hope of defeating it.
>
> *compromising*
> Insincerely ranking an alternative higher in the hope of getting it
> elected.
>
> *push-over*
> The strategy of ranking a weak alternative higher than one's preferred
> alternative, which may be useful in a method that violates monotonicity
> <https://web.archive.org/web/20090613041320/http://condorcet.org/emr/defn.shtml#monotonicity>
>
> *monotonicity*
> The property of a method where an alternative can never be made to succeed
> by being ranked lower on some ballots.  Doing this is using the "push-over
> <https://web.archive.org/web/20090613041320/http://condorcet.org/emr/defn.shtml#push-over>"
> strategy.
>
>
>
> The genius of  STAR Voting is that it apparently technically doesn't
> "violate monotonicity", but it is vastly more vulnerable to Push-over than
> IRV which does, as I've explained previously.
>
> I find the question of whether there have been mistakes or exaggerations
> or false claims made by the IRV promoters to be completely irrelevant to,
> and separate question from, whether its adoption in the US should be
> supported.
>
> Of more concern to me are the details of the ballot rules and
> restrictions. I think it is more democratic for it to be relatively easy to
> get on the ballot so as to allow the voters a wider choice of candidates. I
> understand that typically voters are limited to 7 different "ranking
> levels".  Well say there are 9 candidates and my two least-preferred
> candidates are the two front-runners and I have a preference between them.
> If I vote sincerely my vote is just as wasted as if I had voted sincerely
> in FPP.
>
> IRV then doesn't have Clone Independence.  One of the main points of
> ranked-ballot versus FPP is to reduce the involuntarily wasted vote as much
> as possible.
>
> If such restrictive ballot rules are unavoidable, then I lose my
> enthusiasm for IRV or Benham in favour of something with a truncation
> incentive (and that is happy with equal-ranking if that isn't a problem for
> the ballot rules) such as Smith//Approval (implicit).
>
> Properly implemented Hare's  Compromise incentive is practically nothing
> by comparison with that of FPP, and no-one in Australia notices it.  I
> estimate it is also quite a bit weaker than that of STAR.  Pushover
> strategy in Hare is relatively difficult and risky in Hare and as far as I
> know it's never been tried in Australia.  Whereas STAR is a "festival of
> Push-over" farce/nightmare.
>
> And while (like STAR) it fails Condorcet, it has a solid set of
> "representativeness" criterion compliances that together can be thought of
> as weakened Condorcet and are worth quite a lot.
>
> They are Dominant Coalition (a better stronger version of Mutual Majority
> that so of course implies it) and Dominant Mutual Third and Condorcet
> Loser.   STAR only meets the last of those, the weakest.
>
> Chris B.
>
>
> On 29/04/2024 5:08 am, Closed Limelike Curves wrote:
>
> Michael—you're right that it means favorite-burial (cutting the "head" off
> a ballot). The term is quite old, though (older than "favorite betrayal"
> or "favorite burial" I believe)
> <https://www.cambridge.org/core/product/identifier/S0003055400194481/type/journal_article>
> .
>
> On Sun, Apr 28, 2024 at 12:02 PM Michael Ossipoff <email9648742 at gmail.com>
> wrote:
>
>> Of course I’m just guessing, but my guess is that “decapitation” is
>> Closed’s new name for favorite-burial.
>>
>> Closed sometimes in invents new names without define them.
>>
>> IRV indeed shares Plurality’s need for favorite-burial
>> defensive-strategy. I don’t like that, & wouldn’t propose IRV. There are a
>> number of places where IRV is (the only electoral reform) up for enactment
>> this year, In spite of that very  unlikeable strategy-need, I wanted to
>> help campaign for its enactment, in the hope that the voters who’ve enacted
>> it didn’t do so because they intend to bury their favorite, & so so won’t
>> do so.
>>
>> But, because IRV is being fraudulently sold to them, with intentional
>> lies, we can’t count on how people will vote when they find out about what
>> they’ve enacted…when they find out about the lie.
>>
>> Therefore, regrettably, we shouldn’t support “RCV”.
>>
>>
>> On Sun, Apr 28, 2024 at 11:15 Chris Benham <cbenhamau at yahoo.com.au>
>> wrote:
>>
>>> Limelike,
>>>
>>> Can you please define and explain the "decapitation" strategy?   I
>>> haven't heard of it.
>>>
>>> And can you elaborate a bit on this? :
>>>
>>> IRV is a good example of this. It's *usually* not susceptible to
>>> strategy (in the IAC model), but I think of it as one of the most
>>> strategy-afflicted methods on this list. It's vulnerable to some
>>> particularly-egregious strategies (decapitation), ones that are complex or
>>> difficult to explain (pushover), and many strategies [that?] don't have a
>>> simple defensive counterstrategy available (like truncation).
>>>
>>>
>>> Chris B.
>>>
>>> On 29/04/2024 2:31 am, Closed Limelike Curves wrote:
>>>
>>> Hi Kris, thanks for the results! They're definitely interesting.
>>>
>>> That said, I'm not sure how useful a metric raw probabilities provide; I
>>> don't think they provide a very strong measure of how *severely* each
>>> system is affected by strategy. Missing are:
>>> 1. How much do voters have to distort their ballots? Is it just
>>> truncation, compression (as with tied-at-the-top), or full decapitation?
>>> 2. How hard is it to think of the strategy? Counterintuitive strategies
>>> (e.g. randomized strategies or pushover) require large, organized parties
>>> to educate their supporters about how to pull it off. This could be good or
>>> bad depending on if you like institutionalized parties. Good: sometimes
>>> people can't pull it off. Bad: this creates an incentive for strong parties
>>> and partisanship. See the Alaska 2022 Senate race, where Democrats pulled
>>> off a favorite-betrayal in support of Murkowski to avoid a center-squeeze.
>>> 3. Is a counterstrategy available?
>>> 4. How feasible is the strategy (does it involve many or few voters)?
>>> 5. How bad would the effects of the strategy be? Borda is bad not just
>>> because it's often susceptible to strategy, but because it gives turkeys a
>>> solid chance of winning.
>>>
>>> IRV is a good example of this. It's *usually* not susceptible to
>>> strategy (in the IAC model), but I think of it as one of the most
>>> strategy-afflicted methods on this list. It's vulnerable to some
>>> particularly-egregious strategies (decapitation), ones that are complex or
>>> difficult to explain (pushover), and many strategies don't have a simple
>>> defensive counterstrategy available (like truncation).
>>>
>>> A low-probability but occasionally high-impact strategy might be the
>>> worst of both worlds; voters get lulled into a false sense of security by a
>>> few elections where strategy doesn't matter, then suddenly find a candidate
>>> they dislike elected because they failed to execute the appropriate
>>> defensive strategy.
>>>
>>> ----
>>> Election-Methods mailing list - see https://electorama.com/em for list info
>>>
>>>
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