[EM] IRV vs Plurality Vote with a Runoff

[Anthony Simmons]

>> From: barnes992001 at yahoo.com
>> Subject: [EM] IRV vs Plurality Vote with a Runoff

>>         Does the fact that IRV uses a preference ballot,
>> instead of a repeated ballot, make it less manipulatable?

>> Whatever you believe the answer is, can you prove it by
>> example or argument?

Well, about a year ago, maybe a little less, there was an
election in Queensland, Australia, for state legislators.
One party, One Nation, wanted another party, the Liberals, to
swap preferences (you recommend that your voters put us down
as second preference and we will do the same for you).  The
Libs refused.  In response, One Nation withheld their
preferences from the Libs.  I don't know how much effect that
had, but in Queensland, the Liberals are now the Ghosts of
Elections Past.  As I recall, they didn't even get enough
votes to remain an official party in Queensland.

Anyway, I can see how preference swapping would work
differently in two-round runoff than in IRV.  You can indeed
swap preferences in two-round runoff, but it only makes sense
after the first round, while IRV requires parties to make
their recommendations before the first round.