[EM] Approval Voting vs Instant Runoff Voting:

[Richard Moore]

Martin Harper wrote:

> Right - and I can't see any case where saying you will vote A not AB
> will cause B voters to vote AB. I'm sure such a case exists - but I
> can't find it: hence my question at the end: can you provide one?

Well, there seem to be too possibilities for the effects of these polls. Some
people will disregard the poll and apply a zero-information strategy. Others
will consider the polls before making their final decision, possibly adding a
second choice to their favorite.

If we accept the existence of the second group, then there is plenty of
reason to believe that if some of them like B first and A second, they will
vote AB only if they think A is more popular than B. So if I am an AB voter
(based on my zero-information strategy) and I prefer A to B, then I can
try to court B voters to vote AB by withholding my B vote in the poll. Of
course it helps if there are a whole bunch of us in the same camp playing
this game together.

If we do not believe the second group exists, then I have nothing to lose
by lying in this poll.

 -- Richard