[EM] Modification of STV to guard against favourite betrayal

robert bristow-johnson rbj at audioimagination.com
Mon Sep 9 10:15:27 PDT 2013

On 9/9/13 7:10 AM, Peter Zbornik wrote:
> does anyone of you know if there is any modification known to STV, 
> which makes it satisfy the favorite betrayal criterion?

well, you can make your STV more Condorcet-like by modifying it to be 
Bottom Two Runoff STV  (BTR-STV or BTR-IRV.)

> Some people in our party are unhappy due to the outcome of an election 
> where their favorite was "betrayed".

one of the issues with IRV in Burlington in 2009 was that, contrary to 
the promise of IRV (that you can vote for your favorite without worrying 
about helping to elect your least favorite), was that the folks on the 
extreme right (who i called the "Prog haters in the GOP") found that 
simply by marking their guy as #1 on the ballot, they actually *caused* 
the election of their least favorite candidate which would, if IRV had 
not been repealed, encourage some to betray their favorite.  but in 
Burlington in 2009, if that election was decided by a 
Condorcet-compliant method, this would not have happened.

and the only way i know of to modify STV (and to be able to still call 
it "STV") is to modify it to STV-BTR.


r b-j                  rbj at audioimagination.com

"Imagination is more important than knowledge."

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