[EM] Unranked-IRV

[Richard Moore]

Tom Ruen wrote:

> I've been interested recently in using approval voting to end the spoiler
> effect of plurality elections, but I get objections to the approval process,
> most strongly from Don Davison, that everyone only should get one vote, and
> he's right that is how our current system works. For Don's sake, I
> considered split-vote tied-ranks within IRV. Tied ranks in IRV is completely
> reasonable and can be supported by dividing a vote by the number of
> candidates in the tie.

I don't think Don will be happy with anything less than IRV. Less flawed, that
is.

> Of course, we can later add rankings as a bigger reform and use
> IRV-w/split-vote-tied-ranks or Condorcet-w/tied-ranks later too when we are
> ready for a bigger step.
>
> Does this sound like worthy reform? If it can more often produce a majority
> winner in a single election, then I say the answer is a clear YES!

Unranked IRV seems like it would be a definite improvement over that other
IRV. Why? With the approval vote, all preferences that a voter chooses to
reveal are counted in the elimination process. With ranked elimination, only
the current top preferences are counted. Important information is ignored
so the elimination process is flawed. Partial-information elimination is the
source of IRV's problems. For that reason, I don't think there would be
any improvement in going from Unranked IRV to IRV-Split Ties; in fact,
that would be a disimprovement. If you want to use rankings, it's best to
stay away from elimination methods.

As for comparing Unranked IRV to straight Approval, I don't know which
is better. The first question that comes to my mind is: Will voters have as
strong a tendency to spread their votes among multiple candidates in
Unranked IRV as they would in Approval? The answer will come from
studying voter strategy for Unranked IRV.

> Plurality or Unranked-IRV, which method will you choose for unranked
> ballots?

Right now, I would rank these methods as follows: Approval > UIRV >
Plurality. But I will keep an open mind about UIRV.

 -- Richard