On Mar 16, 2008, at 19:20 , Greg @ Somerville for IRV wrote:
I don't believe that Range Voting will eliminate even the kind of
spoilers that IRV does away with.
Range sure has some weaknesses.
Consider two-candidate race between
Bush and Gore in which 51 voters prefer Gore to Bush and 49 prefer
Bush to Gore. Following the directions given on the RangeVoting.org
website, voters should give a '10' to their favorite candidate and a
'0' to their least favorite:
51 people rate Gore=10, Bush=0
49 people rate Bush=10, Gore=0
the result: Gore=510 > Bush=490 (Gore wins)
Now we re-run the election with Nader in the race. When Nader enters,
5 people for whom Gore was their first choice switch to preferring
Nader. Those 5 voters rate Nader a '10' and push Gore down to '5':
46 people rate Gore=10, Bush=0, Nader=0
49 people rate Bush=10, Gore=0, Nader=0
5 people rate Nader=10, Gore=5, Bush=0
result: Bush=490 > Gore=485 > Nader=50 (Bush wins)
One basic rule is that the best strategy for Range voters is to vote
roughly in Approval style (=only 0 and 10 used). Your example is a
valid concern on Range behaviour and it is quite possible that under
some circumstances the method could pick a bad winner. The Nader
supporters could however learn that their best strategy is to vote in
Approval style Nader=10, Gore=10, Bush=0. This would keep Range still
working (if all the voters can follow this Approval strategy
recommendation).
Range may however fall again when the support of Nader grows. Or we
could talk about the current Obama-Clinton-McCain case where the
approximate first place support of these candidates is 25%-25%-50%.
In this situation especially the Obama and Clinton supporters are in
trouble since voting Obama=10, Clinton=10, McCain=0 (as above in the
Nader example) would mean that they don't take any position at all on
the Obama vs. Clinton question. Range thus is in trouble when there
are two critical questions to answer (Democrat vs. Republican, and
Obama vs. Clinton).
(The Nader case was easier since the voters could maybe quite safely
assume that Nader will not win in any case. In the latter case there
were three potential winners.)
Juho
How could the 5 Nader voters suddenly have a different utility for
Gore? In reality, the rating a voter will give to a candidate isn't
some fixed objective measurement of their happiness with a candidate,
but a rating relative to the options available. In short, everyone
will naturally grades on a curve. To say that RV satisfies IIA is to
ignore the reality that ratings will inevitably be relative.
Thus, Nader would still be labeled a spoiler, because his entrance
into a race causes some to rate Gore lower.
Agree?
Greg
----
Election-Methods mailing list - see http://electorama.com/em for
list info
___________________________________________________________
All New Yahoo! Mail Tired of [EMAIL PROTECTED]@! come-ons? Let our SpamGuard protect you. http://uk.docs.yahoo.com/nowyoucan.html
----
Election-Methods mailing list - see http://electorama.com/em for list info
