Araucaria Araucana araucaria.araucana-at-gmail.com |EMlist| wrote:
Consider this case. Original true preferences:
27: A>B
24: B>A 49: C
A is the Condorcet winner. Now consider what happens if B defects via truncation:
27: A>B 24: B 49: C
Under RP(wv), Beatpath(wv) or DMC, B wins. B voters have gotten a better result by dropping a lower preference. This is an example of the "Later No Hurt" violation of Condorcet completion methods -- B voters hurt their favorite by adding a lower-ranked preference.
But if A puts the approval cutoff above B, B can't win in DMC:
27: A>>B 24: B 49: C
C wins, anyway you cut it, as you found. There's no LNHurt situation here because B can't win either way. So the best the B voters can do is to add a preference for A. That's what I mean by the poison pill (by the A voters). Is it clear now?
Ahhh...yes, now I see what you meant. As you pointed out, however, this particular situation is apparently no worse for DMC than it is for popular (on EM) Condorcet methods (or Approval). Are you saying that, with an approval cutoff (i.e., ranking allowed for unapproved candidates) that DMC actually has an advantage over those Condorcet methods? If so, then I am certainly willing to reconsider allowing an approval cutoff.
Note, however, that the added equipment requirement for an approval cutoff could delay the adoption for decades, but I won't get into that now.
Let me just suggest another possible approach to the problem: auto-truncation. This idea is probably unoriginal, and it is also probably meritless, but let just throw it out there anyway as a long shot. This idea could be applicable to other methods too, but lets just consider DMC/RAV.
Suppose we determine a tentative winner using the standard DMC rules. Now we "suppress" (tentatively eliminate) all the non-first-choice votes for that tentative winner, then determine a new winner. For all the voters who had the new winner ranked above the previous tentative winner, keep that previous winner "suppressed", but for all who didn't, unsuppress (restore) the votes for the previous winner. Repeat until the process converges to a stable winner.
Will this procedure always converge? If so, has it been proposed before, and is it equivalent to some other, perhaps simpler, method?
So a good DMC strategy is
Rank all candidates you are willing to see elected, from your favorite to your "hold-your-nose-and-swallow-just-barely-tolerated" candidate.
Why not just go all the way down?
Put your approval cutoff just below the candidate with the best shot at winning. (I think this is Forest's Approval voting criterion).
Here, that means that the A voters cutoff below A.
B voters, realizing this is the strategy, will add a lower preference for A.
C voters, if they realize they're in the minority, might then decide to rank their preferred opposition alternative below the cutoff. If they despise A, they might actually vote for B in sufficient numbers to turn the election around.
But you don't get this effect if you remove the approval cutoff.
Those schemes might or might not be acceptable. I realize they seem very simple to you, but I think they may still be too complicated for major public elections. Also, I don't like the idea of requiring the voter to actually write a number. That's asking for trouble because the written number will sometimes be ambiguous.
I find writing a number to be much faster than filling in an optical cell!
I don't think optical cells are the answer either. What you want is a nice, simple touch-screen (or mouse based) system. And yes, of course you need to generate paper ballots too.
I envision something like the Graphical Voter Interface (GVI http://ElectionMethods.org/GVI.htm) that I developed a while back
Can't see the screenshots:
Permission Denied
The area you are trying to access has been closed off by the server administrator.
OK, I fixed it. Take a look at it.
just for kicks. It has a column of buttons, each about a half inch high by 3 inches wide, with a candidate's name and party on each one. You select them in order of preference by simply touching them on a touchscreen (or clicking on them with a mouse on a conventional monitor). You can always backtrack, of course. You can specify equal rankings by touching a selected candidate a second time (GVI doesn't currently allow that, but it could be added).
Woowee. Screen takeover. Watch those colors and fonts!
I don't understand what you mean by "Screen takeover."
I'm not sure I find that more intuitive.
Anyway, I favor paper ballot counting, period. Machines would be used only for assistance. What does your software do then?
Yes, GVI can print paper ballots. However, this feature is just a prototype. it just prints the ballot to a conventional printer.
--Russ ---- Election-methods mailing list - see http://electorama.com/em for list info
