[EM] Re: Definite Majority Choice

[Araucaria Araucana]

On  4 Apr 2005 at 23:39 UTC-0700, Russ Paielli wrote:
> I was just looking at the wiki page for DMC:
>
> http://wiki.electorama.com/wiki/Definite_Majority_Choice
>
> I saw this statement:
>
> "DMC chooses the same winner as (and could be considered equivalent in
> most respects to) Ranked Approval Voting (RAV) (also known as Approval 
> Ranked Concorcet), and Pairwise Sorted Approval (PSA)."
>
> Do we know for sure that DMC always chooses the same winner as RAV and
> PSA? If so, then in what respects are they *not* equivalent?

Before commenting on a wiki page, please note that you might have to
purge your browser's cache and reload the page to get the latest
version.  I've run into this problem recently myself.

The excerpt you cite is due to my suffering from the same affliction
as old what's-his-name, uh, John Kerry: I can't resist inserting every
possible mathematical qualification into what I'm describing.  I
should probably take out the first parenthetic remark, as it serves no
purpose.  I may have done so by the time you refresh your browser,
in fact.

DMC, RAV and PSA are all equivalent in the sense that they choose the
same winner.  Period.  This is the same kind of equivalence as CSSD
being equivalent to Beatpath.  The way that they are not equivalent is
that they don't follow exactly the same path to get to that winner.

I happen to think that DMC is the simplest-to-grasp version of all
three methods.  Here is one way to find the winner:

      Eliminate any candidate defeated by another candidate with
      higher total approval.

      Among the remaining candidates, the candidate with the lowest
      approval defeats all others and is the DMC winner.

Everyone is familiar with the idea of most or least points, so a voter
looking at the pairwise array could find the winner in a few seconds,
by inspection.  No mention of Smith sets, no ranked pairs, no fancy
algorithms, clean and simple.

>
> If these methods are equivalent, then I think we need to eventually
> try to somehow agree on a common name for public promotion. We might
> also be wise to agree on the simplest explanation, with the more
> complicated explanations used as "backup" material for those who are
> intellectually curious.

Yes, of course.  But see above -- can you get simpler than that?

>
> The actual name and acronym may be critical to the public salability

'marketability' might be the word you're after.

> of the method, so we need to be very careful in selecting it. We
> shouldn't rush into it. "Definite Majority Choice" seems too generic
> and not descriptive enough to me, but I am not necessarily opposed
> to it. I like RAV (which I proposed myself), but I don't consider it
> an ideal name either. In any case, we must avoid at all cost using
> the word "dropping" in the name (it sounds too much like something
> birds do).

Well, Condorcet was called 'true majority rule' in the March 2004
Scientific American article.  The DMC winner is chosen from candidates
remaining after eliminating definitively defeated candidates.  So if
you want to quibble, Definitive Majority Choice might be more
accurate.  But I think we want to avoid having more than one
4-syllable word in the name ;-).

Yes, the name can be important.  But you have to watch out for the
initials also.  For example, I was thinking of something called
Pairwise Ordered Sorting a while back and realized POS would be an
unfortunate acronym.

> One of these days I should crank out a list of possible
> names/acronyms of this method for discussion and perhaps an eventual
> vote.

If you don't mind, I would recommend focusing your efforts on
understanding the method first.  Compare especially to PSA and
Approval Sorted Margins.

I think Approval Sorted Margins is the best alternative to DMC from an
anti-strategic standpoint.  Note that no change would be required in
the ballot to switch from DMC to ASM, and it uses the same pairwise
array with total approval on the diagonal.  I have yet to see a case
in which ASM gives a different result than James' AWP or Chris
Benham's AM.  I would prefer to see ASM reduced to a much more concise
form before considering it as a first public proposal, but it could be
proposed as a more secure alternative after the DMC ballot is adopted.

-- 
araucaria dot araucana at gmail dot com