[EM] Re: why ranking should be allowed for approved candidates only

[Araucaria Araucana]

On 20 Apr 2005 at 22:51 UTC-0700, Russ Paielli wrote:
> Ted,
> I'm still not getting it. Let me lay out my calculations more explicitly
> just to be sure I'm not making any silly mistakes. I'll use "|" to 
> indicate the approval cutoff (I like to be different).

<snip>
>
> Do you agree with these results?

You're missing the point, which is, how does approval cutoff change
the result?  You would have seen what I meant if you had changed the
cutoff to a simple ">" ranking.  I will summarize this well-discussed
example for you.  It is worth careful study.

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?

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.

   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 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.


> 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'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?

>
> Remember that there is little or no time for "training," so the
> interface needs to be as simple as possible -- especially for
> Democrats! 8^)

No slurs, please ;-).  Techno-illiterates come in all stripes.

Ted
-- 
araucaria dot araucana at gmail dot com