For some unknown reason, Jameson responded with a new subject header,
instead of to my original EMAV proposal, so I'm copying that at the
end of this post.
At 10:13 PM 6/30/2013, Jameson Quinn wrote:
Abd proposed Bucklin//Score, which he dubbed "evaluative majority
approval voting". My first, and still my principal, response was:
that's not bad, and if you can build were a consensus behind that,
I'll sign on. I'd still like to see Abd respond to that ( and
ideally commit to first mentioning a consensus Bucklin proposal once
per thread before discussing the relative merits between Bucklin
systems) before engaging with the specific discussion below.
EMAV is Bucklin. As proposed, it's three-rank Bucklin. An additional
rating is added for full utility expression.
Hence, under certain conditions, it is Range. The minimum rating is
the default No, which could be explicit.
Under those conditions, the rating values could be 2, 1, 0, -1, -2.
The ballot is a range ballot. The Bucklin evaluation is median Range
except with ties, which are resolved with the social utility
informoation from the ballots.
My basic response to EMAV specifically is: Bucklin is good and Score
is good, so it's not bad, but it's still in some sense the worst of
both worlds.
It addresses the most significant problem of Range, majority
criterion failure. The method is MC compatible. Yet it collects full
Range data (and with interpolation and the explicit min rating, it
would be a Range 8 ballot, very close to the commonly-proposed Range
9. Range 9 *could* be used. But the interpolation idea -- not
essential -- keeps the ballot simpler.
Not as responsive or simple as Score,
I'd disagree. It is more responsive than Jameson's proposal, MAV,
which dumps and does not use the utility information available, if
there is a multiple majority. EMAV decides a multiple majority based
on the utility information. It is *very* easy to understand, and
intuitive understanding is quite likely to be correct. It's Bucklin
(which was easy to understand) and Range (also easy to understand.)
It will collect full Range data; the *basic voting strategy* is to
vote a sincere Range ballot, same as Range, i.e, Range with the usual
"max-rate favorite frontrunner, min-rate worst frontrunner" strategy.
It allows clear distinction of the Favorite from the preferred frontrunner.
(Remember, multiple majorities in first rank will be extraordinarily
rare, we should be so lucky. Anyone concerned about Favorite
Wimpiness (equal ranking is not a betrayal, as such), can easily
defer that additional approval to second or third rank.)
not as exaggeration or chicken resistant as most Bucklin methods,
it's just a compromise that will make nobody really happy.
1. "Exaggeration" is a made-up story. People extreme-rate when they
have strong preference. That preference may be *simple,* such as "I
don't know any other candidates and I don't want to give any voting
strength to an unknown," or "I only vote for Democrats," but it *must
be* a strong preference, or they would care about risk of the second
preference beating the first. They'd be pleased to see the second
preference win. "Exaggeration" is also used to describe *normal
social choice.* I.e., we choose among realistic alternatives, and our
"rating" of them depends on what we see as realistic. It's
"strategic." And voters who vote absolute ratings will mostly be
fooling themselves or disempowering themselves.
2. "Chicken resistant" is also a made-up story based on our
imagination of how a voter faces a strategic choice. There is no
speeding car heading toward us. There are options and assessments of
probabilities. There is no other driver we are competing with. And
it's just one vote. There are simply different methods of determining
the winner if there is a multiple majority. EMAV is practically
identical to MAV except with multiple majorities and the use of range
rather than pure reduction to approval, losing all that utility
information, when majority approval has not appeared. What are the
two alternatives that supposedly create a "dilemma"?
1. Add B as an additional approval to our favorite A. Bucklin and
EMAV allow two lower preference levels for this, which would
rationally correspond to preference strength, with the minimum
preference level indicating approximation to election expectation.
Remember, if there is another candidate, C, whom we fear will win,
our election expectation has gone down, so a mid-rating will be more
appropriate for B than otherwise.
2. Do not add B, risk the election of C. EMAV provides multiple
levels of response to this situation, which are then balanced with
(1). How the voter actually votes will depend on preference strengths
in the three pairs and the election expectation.
Bucklin hybrids can work well; Bucklin//Condorcet, for instance,
is in many ways best of both, though its counting complexity is a
bit high for me. But if EMAV is better than MAV, then Score is even
better; while if EMAV is better than Score, then MAV is even better.
The problem, Jameson, is that ordinary Score misses something, called
Majority Approval, a basic element of democracy. It's a complex
issue, and it may, in fact, make little practical difference, in many
elections, but the principle of majority consent to decisions is
quite basic and is a widespread idea; therefore getting Range
implemented, just like that, is likely to be difficult, because MC
failure *will* be asserted as a counter-argument.
EMAV begins collecting Range data, and uses Range evaluation for
median tie-breaking (and plurality resoluttion), so it would break the ice.
I'm going to guess that SU study of this method, with proper
application of voting strategy, would take this down to
*almost-Score* Bayesian Regret. I've also argued that Range should
include an explicit approval cutoff, which this method effectively
incorporates and uses.
As you know, I would greatly prefer to complete with majority
approval, and thus I'd see this method, or Range, used with a runoff
if there is no majority approval shown. Ultimately, if it's a
two-round system intrinsically (the first election is really a
nomination primary), this could be the second round. The first round
would also work, but I'd want to see Condorcet testing, both with
EMAV and MAV, in the first round. Not the second.
original post on EMAV
From: Abd ul-Rahman Lomax
Date: Fri, 28 Jun 2013 10:06:10 -0500
The other day I sent this post to the mailing list for the Center
for Election Science ([email protected]). Comments
are very welcome.
------------------------
Okay, from discussions on the EM list, I've come to a method that
seems practically ideal to me. We can call it EMAV, Evaluative
Majority Approval Voting.
It uses the fact that a Bucklin-ER ballot, sanely voted, represents
a descending approval cutoff; therefore the ballot
1. Expresses approval explicitly for all candidates so categorized.
2. Expresses preference *strength*, tied to approval cutoff, which
is, from a common suggested approval strategy, rooted to election expectation.
The method:
1. Ranked ballot, with three approved ranks, one explicit
disapproved rank, and default maximally-disapproved rating for blanks.
2. The ranks are ratings, with values of 4, 3, 2, 1, with 0 being
default. A rating of 2 or higher is approval. (so rank number is the
inverse of rating.)
3. Voters categorize candidates into categories, corresponding to
the ranks (ratings), and may categorize as many candidates as they
choose into each category. Categories may be empty.
4. The count of all legal ballots is the basis for "majority."
5. MAJORITY SEEKING. Canvassing begins with the first rank. If a
majority of voters have so categorized a candidate, and no other
candidate, the election is complete and that candidate wins. If more
than one candidate has a majority, see the Evaluation process.
6. If no candidate has a majority in the first rank, the number of
second rank votes is added in to the previous sums, and majority
support is again tested as with the first rank.
7. If no candidate has a majority in the first and second ranks
combined, the number of third rank votes is added in to the previous
sums, and majority support is again tested, as with the first rank.
8. EVALUATION. Vote evaluation is performed if there is no majority,
or if the above process finds more than one candidate with a
majority at a rank amalgamation. For each candidate, all the cast
votes are summed, using the rating values. If there are multiple
approved majorities, from the prior process, the winner is the
majority-approved candidate with the highest sum of ratings. If
there is no majority approval, the winner is the candidate with the
highest sum of ratings.
Notes:
This method is "almost Range." In a runoff system, with runoff
conditional on lack of majority approval, it could send top approval
and top range candidates to the runoff. It could also be pairwise
analyzed to send a Condorcet winner to the runoff.
As a runoff method, the voters will now presumably be much better
informed about the candidates. The candidate set will likely be
reduced. This method is safe from ordinary Favorite Betrayal in a
runoff. (There are very unusual situations that could require
strategic equal-rating, they involve multiple majorities. In the
primary, there are other rare situations where some level of
strategic voting is required; intrinsically, the way that many
define "strategic voting," any use of "election expectation" is
"strategic." In a runoff system, voters would presumably vote
conservatively as to adding additional approvals, those with strong
preferences. That's rational and *does express real perference
strength.* That includes "bullet voters," based on only knowing the
Favorite. A runoff gives these voters a new look at the candidates.
If someone the best candidate is not nominated for the runoff, a
write-in campaign would be based on actual knowledge of voter
preferences. A Condorcet winner, for example, if Condorcet testing
is not done, could still be visible from the votes if they are all
reported, and if those preferences are maintained, and voted with
knowledge, this candidate should win the runoff.)
If there is Condorcet failure with this method, it is likely to be a
case where the Condorcet winner is *not* optimal.
The canvassing is simple to understand, I suspect. This is Bucklin,
purely, unless there is majority failure, or a multiple majority, in
which case it becomes Range (completely or within the majority-approved set).
This method could, of course, be trivially adapted to use more
rating categories. I suggest that they always be balanced between
approvaed and disapproved ratings, with midrange being considered
"barely" approved, if it is Range N, N being even. If N is odd, then
there is no midrange rating.
Unless the previously suggested overrating method is used to allow
half-ratings. (This method would allow a voter to express
half-ratings by voting two adjacent ratings. It handles what would
otherwise be overvotes by counting the vote at the average of the
top and bottom rating expressed.)
So if the method used a Range 9 ballot, voting the ratings of 4 and
5 would be considered a vote of 4.5, thus midrange, and a
'stand-aside' approval. This is a trick for almost-doubling the
resolution of a range method. Explicit zero might be added to the
ballot if this is used, that would then allow doubled disapproved rating.
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