[EM] Why I think IRV isn't a serious alternative 1

[Kevin Venzke]

Hi,

I will have to try to keep my responses briefer as I am short on time.

--- En date de : Jeu 4.12.08, Abd ul-Rahman Lomax <abd at lomaxdesign.com> a écrit :
> De: Abd ul-Rahman Lomax <abd at lomaxdesign.com>
> Objet: Re: [EM] Why I think IRV isn't a serious alternative 1
> À: stepjak at yahoo.fr, election-methods at electorama.com
> Date: Jeudi 4 Décembre 2008, 13h23
> At 09:07 PM 12/2/2008, Kevin Venzke wrote:
> 
> > > This is the "relatively objective method of
> > > assessing" election outcome. When it's
> easy to
> > > determine, in a real situation, the absolute
> individual
> > > voter utilities, "fully sincere Range
> Voting"
> > > implements it as a method. That is, if the voters
> are
> > > honest, or if their "votes" are
> determined for
> > > them by some objective method -- such as a
> measurement of
> > > tax impact based on, say, the previous year's
> income tax
> > > return -- this obviously would produce an
> objective result
> > > that could be considered ideal. In real
> elections, of
> > > course, determining absolute, commensurable
> utilities may
> > > not be possible. (There are voting systems
> involving
> > > lotteries and real bets made by voters that
> should encourage
> > > the voting of absolute utilities, but these
> aren't being
> > > considered here.)
> > 
> > In your previous message you seemed content to say
> that voters can't
> > vote "accurately" under Range because they
> don't know how and because
> > the ratings have no inherent meaning.
> 
> The two considerations should be kept rigorously separate.

I don't see how they can be kept separate if you want the one to
say something about the other.

> We can study voting systems using absolute utilities that
> are *assumed* in a simulation. The absolute utilities allow
> the prediction of voter behavior under various models. We
> can convert absolute utilities to Range Votes. Want to
> actually maximize overall voter satisfaction. Somehow
> arrange for absolute utilities to be voted. The
> "ideal" winner may be determined using absolute
> utilities, in a simulation. Then voting systems, with
> various "strategies" -- read "methods"
> -- used by the voters to translate their real preferences,
> including real preference strengths -- i.e., the simulated
> ones -- into votes in a voting system, and Bayesian regret
> is defined as the difference in overall, summed absolute
> utilities generated by the difference between the voting
> system winner and the best winner from the summed absolute
> utility standpoint.
> 
> This regret is not minimized by normalized Range, which is
> how we imagine most voters will vote, because of the
> normalization, which equates the votes of voters with
> *overall* weak preferences for the entire candidate set,
> with those with strong preferences over this set. However,
> we get reasonably close, because the normalization error
> more or less averages out. And we preserve "one person,
> one vote," which is politically desirable.
> 
> That's an objective method of studying voting system
> performance. Strategy comes in when translating voter
> absolute utilities into votes.
> 
> From the absolute utilities, we can generate preference
> lists, even more accurately than a voter could.

That is the *problem*.

It's useful in that it helps you measure performance, but with Range it
is a hindrance, because you don't know how accurately voters will
actually be able to vote.

> But if I want to increase the accuracy of the vote, which
> may not maximize my personal utility (it's not likely to
> harm it much, if at all)

Well, to say it again, one's entire vote is usually completely impotent.
In general how much will it hurt you to vote for 3rd place under FPP?

> > > So: How does Range, with realistic voting
> patterns, compare
> > > with other methods. Range does *not* produce zero
> regret. It
> > > produces relatively low regret. If fully sincere
> voting
> > > could be somehow guaranteed -- probably
> impossible -- it
> > > would always choose the ideal winner (within
> certain
> > > restrictions, basically normalization). So there
> are two
> > > deviations from the ideal. The first is from
> normalization,
> > > and the second is from strategic voting.
> > >
> > > Range *with strategic voting* is better with
> respect to
> > > regret than any other method that has been
> simulated, to my
> > > knowledge.
> > 
> > If this is true it can only be by comparing strategic
> Range to strategic
> > (insert rank ballot method), which is at the mercy of
> Warren's
> > understanding and implementation of rank ballot
> strategies.
> 
> Yes. Except that it is only at Warren's understanding
> if others don't exercise themselves to confirm the
> approach. Given that this is the only approach that has any
> hope of being objective, and that little additional work has
> been done, apparently, it shows how much people care about
> objective comparison of voting systems. Not much. They'd
> rather plump for their favorite, perhaps.

The problem is that an objective comparison (especially one that is
suitable for all methods) is going to be extremely difficult and will
always be open to attack when people don't agree with the assumptions.

Warren's approach could be useful when:
1. they simulate realistic voter profiles (and some of them apparently do,
but again, anyone can argue about whether they really are realistic)
2. they simulate nomination strategy that is customized to the method
3. they simulate voter strategy that is customized to the method
4. they simulate pre-election information
5. they can simulate other rank ballot formats that allow equal ranking
and truncation.

In their current state I don't think the numbers can be used except for
the "sincere" methods and potentially for strategic Approval.

> The comparisons have been done, by Warren. His work is
> published and should be verifiable. If not, I'm sure
> that reasonable questions unanswered by his publications
> could be addressed here or on the Range Voting list. If they
> couldn't be answered, that would radically impeach his
> work, wouldn't it?

I've listed deficiencies here and probably there. There are no questions
that need to be answered. The simulations just need to be improved.
They need a lot of improvement and I doubt it's worth it to him.

Some of this isn't difficult, it's just again a question of how far you
take it. Strategic voter behavior needs to be made less ridiculous.
But what kind of strategy should be allowed, for (let's say) Condorcet
methods? If everyone votes sincerely, then Range will look bad. So
clearly the line has to be drawn somewhere else.

> Essentially, poor simulation -- if it is poor -- is better
> than none.

I'm not sure why you say that.

> If the simulation were designed to make Range
> look good, that would be one thing. But it appears that the
> reverse is true: Warren went for Range Voting because
> simulation work -- as well as theoretical work -- showed it
> to be ideal, with sincere votes (it must be! -- with the
> right definitions of sincere). He didn't set out to
> prove Range was best, he wanted to know.
> And he wanted to answer the question of "how
> much." How much is, say, IRV better than Plurality? Or
> Approval than IRV or Bucklin? Voting systems criteria
> don't even begin to approach this.

But if we can only accurately measure methods in the case that voters
are sincere, I'm not sure it's very useful.

> It's too much work, and get it wrong, you can seriously
> regret your insincere votes! 

But if you're doing it correctly, you've decided that your expectation
is better by voting insincerely. You can regret a vote no matter what
it is.

> I don't think that
> Warren's work covered this difference: voters who vote
> strategically are likely to be those who have stronger
> preferences. 

Well, if you vote strategically, you are not "playing nice" for whatever
reason. (Either you don't want to, or you haven't read the Range Yahoo
forum and didn't realize you were hoped to.) So it need not be that
you have stronger preferences, it's just that you don't care about the
other voters' input.

I am not sure if Warren ever argued that strategic voters are more likely
to be sociopathic (etc).

> > > Now, to prevent the advantage that knowledgeable
> voters
> > > would have from being able to vote accurately,
> should we
> > > damage the outcome averaged over all voters?
> > 
> > How is it even clear that it would be damaged?
> 
> That's what the simulations show, and nobody has
> controverted that result. It's quite reasonable, by the
> way, it's not likely to be generally wrong. How
> carefully have you looked at this work, Kevin?

What I was getting at was again the lack of basis for trying to vote
accurately. Plus the inability of the voter to accurately determine
all his ratings. When people use the intermediate ratings, the data
could be garbage, and we would never know. This isn't a question that
simulations can answer decisively.

Kevin Venzke