[EM] Keeping Candidates in Subsequent Rounds of Instant Runoff Voting

[Kevin Venzke]

Hello York,
It's not a stupid idea at all, it's intuitive and pleasing and I guess that many of us have thought of it. However, it damages one of IRV's major strengths, which means one can't propose it as a strict improvement.
The problem is that under IRV, you may vote "A>B" and have confidence that your vote for B will not be used until A is no longer an option. But if "eliminating" A does not mean that A is actually removed from contention, there is a possibility that your lower preference for B will help to elect B, when if you had only voted "A" (a bullet vote), the method would have elected A. This could cause voters to be more reluctant to express lower preferences.
This is not to say that I think the method is worse than IRV. It's just that it becomes a different type of method where there are a lot more ideas to compete with (many Condorcet methods, Bucklin, approval-elimination runoff, etc.).
Kevin

      De : York W. &/or Lois G. Porter <porter at kih.net>
 À : election-methods at lists.electorama.com 
 Envoyé le : Vendredi 12 août 2016 15h24
 Objet : [EM] Keeping Candidates in Subsequent Rounds of Instant Runoff Voting
   
Friday, August 12, 2016
3:05 pm CDT

Hi,

I'm a big time "newbie" here. Wasn't able, for some reason, to search the 
existing messages so I thought I'd stick my neck out and ask a probably 
stupid question.

In the IRV election method, I don't understand the rationale of eliminating 
the lowest vote getter in each round. In a simple example, let's say there 
are four candidates. Let's say A, B, and C get thirty percent of the vote 
on the first round. Candidate D gets ten percent. Normally Candidate D is 
eliminated even though s/he might be the choice of 90 percent of folks in 
the second round.

Wouldn't it make sense to simply just leave everyone in each round and 
continue to run the tally until someone has a majortity? If more than one 
candidate, if the thing drug out, got a majority, one could use the one 
that was the "most popular" (had the greatest total) at that point. If 
there was a tie after at least two candidates had a majority, one could use 
"drawing lots".

I'm sure there is something I'm missing here but the eliminating of a 
candidate that might be  basically relatively popular and a good compromise 
candidate seemed to be a problem to me. Apologies if this one is totally 
stupid. I've searched on-line without success at finding the answer. One 
expert wrote back that it would cause problems but didn't specify what the 
problems would be. Any help clarifying this for me will be appreciated.

Thanks,

York



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