[EM] So I got an email...
Kevin Venzke
stepjak at yahoo.fr
Sat Apr 9 20:48:55 PDT 2022
Hi Robert,
I don't think jump ball is a real voting term. I assume he wants to talk about a
tied situation so that he doesn't need to specify what Condorcet method is being
compared.
However, if the IRV advocate wants to point out that Condorcet methods are
susceptible to burial while IRV is not, he will always be able to find some
scenario to show it.
> Preferences (strategic, both major campaigns)
> ABC - 40%
> BAC - 40%
> CAB - 10%
> CBA - 10%
>
> C is no longer the condorcet winner, as both A and B seem to defeat C by 8-020. The winner
> will be decided by a jump ballot tally between A and B. Strategy worked
I think we should say the strategy "works" (i.e. for both of the 40% blocs) only
if they both prefer the coin flip over the election of C.
And actually, as you show below, it may be pessimistic to assume the alternative
to the coin flip is the election of C.
> Let's suppose only one side decides to do this. It probably backfires, but still gives them
> a chance depending on the tiebreaker., So you might get:
>
> Preferences (strategic, only 1 major campaign - backers of B)
> ACB - 40%
> BAC - 40%
> CAB - 10%
> CBA - 10%
>
> Condorcet: C over B 60-40 but A over C 80-20 and jump ball with A and B. So B voters may
> end up helping A win if they lose the jump ballot, they create a cycle and then win an IRV
> tiebreaker if they win the tiebreaker between A and B.
Yes, that has high likelihood of backfiring and electing A. In fact if the method
satisfies Schwartz, there is no tie. A is the only candidate in the Schwartz set:
A has a beatpath to both B and C, which neither can return.
In general a line of thinking like "C is probably going to win, let's try to make
C lose" seems a little suspect, or not fully fleshed out.
Kevin
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