Forest--
You wrote:
Here's the weakness of SR:
60 ABCDEF
40 BCDEFA
Here A should be the winner, but B has by far the best SR score of only 60
versus A's lousy 200.
I believe that this defect is called "teaming."
I reply:
Yes, SR shares that Borda problem, because SR is closely related to Borda.
It's a strategy-proneness. But I'd only advocate SR for electorates who are
terribly strategy-inclined anyway. SR deals with equal top ranking in a way
that avoids dilemma for acceptable/unacceptable strategizers. And with
power-truncation, SR would avoid bottom-end dilemma for strategizers. I'm
mostly concerned about strategizers who perceive an acceptable/unacceptable
situation. (I abbreviate that a/ua).
So I offer SR only for public elections, with determined LO2E voters who
favorite-bury when they can't be reassured that there could never be reason
to do so.
Well, for such voters, Approval is ideal (if it were only more publicly
acceptable). But maybe people insist on a rank method.
SR's Borda-like strategy problems aren't so bad, for an electorate who are
determined to strategize anyway. Of course I prefer MDDB & MDDA, which meet
SFC in addition to FBC. That way, the LO2E favorite-burier won't have to
favorite-bury, but others who are more sincere can benefit from SFC.
Of course the person who really needs FBC isn't going to have need for SFC,
and that is my jutification of SR in public elections.
Of the criteria that are important to me, SR meets only FBC. I'd probably
rather have Approval, if we disregard the matter of acceptabilty. Well, who
knows which would be more acceptable, Approval or a new rank method.
In SR, Borda, and RV, sincere voters could be had by insincere voters. It's
been pointed out that sincere voters in RV could improve the result. But not
when they're had by strategizers. I consider that a serious problem, but I
nevertheless advocate RV as the best public proposal, because of its
unmatched winnability.
Approval doesn't have that problem, because there's only one
rating-difference that one can vote. I personally prefer Approval for that
reason, for public elections, but advocate RV as the best public proposal.
Since SR shares that problem of RV, and (so far as I know) meets none of my
favorite criteria other than FBC, I don't consider SR to a be very good rank
method, when used by itself. If people insisted on a rank method, and, for
simplicity, it had to be a 1-part method, so that MDDA & MDDB were out, then
I'd advocate SR, because that would be a way of getting FBC.
Otherwise, for pure merit, it's probably no more desirable than RV, and, for
pure merit, less desirable than Approval. (and of course a lot less winnable
than RV).
One small advantage of SR over RV: Though strategists could take advantage
of sincere voters, there isn't as much temptation for unconscious strategy,
because voters aren't asked to judge ratings. Voters are only asked to rank
the candidates. So if the voter doesn't consciously decide to strategically
falsify his ranking, the ballot just has reliable ordinal information, not
subject to the voter's judgement, and avoiding victimization of sincere
voters by less-sincere voters, at least when conscious falsification doesn't
take place. That advantge may be of some value.
I don't know if SR's Borda-like problem would be a problem in MDDB. Maybe it
would, and, if so then MDDA might be better than MDDB.
Anyway, I prefer MDDA & MDDB to SR.
And, as I was saying before, I suggest BeatpathWinner or CSSD for committee
and organizations.
Even though a small organization can have a really undesirable candidate,
and FBC compliance would be convenient then, FBC doesn't become really
necessary unless there are voters who are inclined to favorite bury, and who
are seriously mistaken about what is acceptable. (To be more objective,
maybe I should say "...and when voters sharing a last choice differ
drastically on what is acceptable).
That's definitely true in our public political elections, but probably not
in most organizations or committees.
So, though MDDA or MDDB also seem good for committees and organizations,
their FBC compliance isn't so necessary, and BeatpathWinner's GSFC is a
bonus. And, to a lesser extent, its Condorcet Criterion and Smith Criterion.
So it seems to me that BeatpathWinner & CSSD win the comparison for such
use.
Mike Ossipoff
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