[EM] IRV in action

Alex Small asmall at physics.ucsb.edu
Wed Apr 2 10:52:19 PST 2003

Adam Tarr said:
> James Gilmour wrote:
>>But the thinking behind the use of the word in this context is also
>> instructive.
>>You have to remember that IRV is nothing more than a convenient method
>> of condensing an exhaustive ballot into one voting operation.  (It also
>>  avoids all
>>the horse-trading that typically takes place between the successive
>> rounds  of an
>>exhaustive ballot, but that's a different issue.)
> Some have argued that this "horse trading" allows compromise candidates
> to  stave off defeat.

I wonder if people will be more aware of the strategic aspects of runoff
voting if it is done with successive elections rather than a single round

Save we have 3 candidates, and in pairwise contests B>A, C>A, B>C.  If B
is running last in the count of first-place votes, we all know that IRV
gives individuals with the preference A>B>C to insincerely rank B first. 
Same for 2-step runoff (which is formally equivalent to IRV with 3
candidates, although not with 4+ candidates).

When is a voter more likely to think "I need to make sure my conquering
compromise makes it into round 2 rather than my doomed favorite":  IRV or
2-step runoff?  I don't claim to have an answer to that psychological
question, but it would be interesting if somebody has done that study.

My hunch is that 2-step runoff encourages clearer thinking on the issue,
but that is just a hunch.  I'm not claiming 2-step runoff is overall
better than IRV, just that there's an interesting psychological question


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