[EM] Evaluative Majority Approval Voting
Abd ul-Rahman Lomax
abd at lomaxdesign.com
Fri Jun 28 08:06:10 PDT 2013
The other day I sent this post to the mailing list for the Center for
Election Science (electionscience at googlegroups.com). 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.
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.
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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