[Election-Methods] Fwd: [LWVTopics] IRV Voting

[Chris Benham]

Kathy Dopp wrote:

Kathy Dopp kathy.dopp at gmail.com 
Sun May 11 22:00:28 PDT 2008 

"The thing that made me oppose IRV was when I tried out some scenarios
in a spreadsheet and found out that IRV can put the candidate "Least"
favored by voters (favored by the smallest number of voters overall)
into office and so I believe can help the least favored of the two
major political parties gain control of our government, despite the
wishes of voters."
If the first of  these claims is based purely on the rankings given on the
ballots (instead, say, of voters' private ratings) then it is wrong.
IRV (referring to the Alternative Vote as I recently defined it*) meets several
good  "representative" criteria, one of which is Condorcet Loser.

"A candidate that pairwise loses to all others can't win".
Kathy refuses to precisely define what she means by  "favors".

The candidate with the fewest top preferences will be eliminated.
A candidate that has no pairwise victories can't win.
49: A>B
02: B>A
22: B>C
27: C>B
In the IRV election  B is eliminated and  A wins. I've adapted this to 
make the voters's rankings generally as favourable as possible for B and 
as unfavourable as possible for A (without causing A to not be the IRV winner).
Perhaps by "favors" Kathy means "rank above bottom".  B is so ranked
by 100% of the voters, A by 51% and  C by 49%.   The IRV winner isn't
here by this definition the candidate "favored by the smallest number of
voters overall". (C is).

Kathy's second claim is very strange. IRV meets  Dominant Mutual Third.

"If more than a third of the voters rank a subset T of candidates above all
others and all members of T pairwise beat all non-member candidates,
then the winner must come from T."
If one is primarily concerned that the "most favored" of the two major political
parties wins, then IRV is certainly  a good method.
Chris Benham

* The  Alternative Vote :
voters strictly rank from the top however many or few candidates they wish,
until one remains eliminate the  remaining candidate that is top ranked among 
remaining candidates on the fewest ballots.


      Get the name you always wanted with the new y7mail email address. www.yahoo7.com.au/y7mail