I just want to repeat a suggestion I've made here more than once. Take my
previous example where the Centre-Right candidate is elected due to some of the
Left candidate's supporters using the Compromise strategy.
49: Right
28: Centre-Right (7 are sincere Left>Centre-Right)
23: Left
Centre-Right beats Right in the runoff 51-49.
But the Right supporters have an easy Push-over strategy to (from their
perspective) "rectify" this.
If anywhere between 6 and *all* of them change their vote to approving both of
Right and Left, then Left will be dragged back into the runoff with Right and
then be beaten.
My suggested 2-round method using Approval ballots is to elect the most
approved first-round candidate A if A is approved on more than half the
ballots, otherwise elect the winner of a runoff between A and the candidate
that is most approved on ballots that don't show approval for A.
This destroys the incentive for parties to field 2 candidates, and greatly
reduces the Push-over incentive
(to about the same as in normal plurality-ballot Top-2 Runoff).
Chris Benham
----
Election-Methods mailing list - see http://electorama.com/em for list info
