[EM] Runoff vs IRV

[Alex Small]

On a purely technical/strategic/theoretical evaluation I prefer IRV over
runoff.  I understand Mike's point about how a CW in the top 2 (of round 1
in runoff, and before the first elimination in IRV) will always win in
runoff, but he could lose in IRV (if there are 4 or more candidates). 
However, I could easily turn it around and point out that a CW who is
_not_ in the top 2 will always lose in runoff, but he might still win in
IRV if the first elimination transfers some votes to him.

What cinches it for me on the strategic/theoretical side is that IRV
allows voters to provide more than runoff, and also takes advantage of
that information.  Yes, yes, I know, many will point out that other
methods (e.g. Condorcet) use even more information than IRV, but Mike
specifically limited his consideration to IRV vs. runoff, and I'm
following in that spirit.  Of course, the amount of information used is
not the only criterion to consider, but when the methods are otherwise so
similar it may be an important one.

On the practical side, I have mixed feelings.  Runoffs are obviously
expensive, but if in an election cycle 2 elections are already scheduled
to occur within a few months of eachother (e.g. primary and general
elections) then runoff incurs no added expense.  IRV, however, requires
new equipment.  And Bart makes a good point about allowing voters more
time to evaluate the 2 finalists.



Bart Ingles said:
>
> Runoff also has the advantage of allowing the voters to learn more about
> the finalists before the runoff election.  Not a major advantage
> compared to what can be gained with other systems, but since Runoff and
> IRV are otherwise fairly similar...
>
> Bart
>
>
> MIKE OSSIPOFF wrote:
>>
>> Though it would be hoped that we'd get something better than Runoff or
>> IRV, what if it were necessary to choose between those 2?
>>
>> Of course they both have advantages compared to eachother, and
>> examples in which they do better than the other.
>>
>> But what stands out, for me, is that Runoff always elects a CW who
>> comes in 1st or 2nd in the initial Plurality count, whereas IRV can
>> fail to elect a CW who is favorite to more people than anyone else is.
>> [...]
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