[EM] [ApprovalVoting] Re: The IRV-Disease has reached my town.

[Juho Laatu]

> On 05 Mar 2019, at 07:45, Chris Benham cbenhamau at yahoo.com.au [ApprovalVoting] <ApprovalVoting at yahoogroups.com> wrote:

> Robert,
> 

> 
>> in a ranked ballot, what defines an "approved" candidate?  all unranked candidates are tied for last place on a ballot.  is any candidate that is ranked at all "approved"?
> Yes.
> 
>> that would change and complicate the meaning of the ranked ballot.
> 
> Arguably "change" somewhat but I don't see how (overly) "complicate". Allowing voters to rank among unapproved
> candidates makes the method more vulnerable to strategy and a lot more complicated.
> 
One might face problems sooner with sincere voting than with strategic voting.

First preferences could be as follows.

30: far-left
21: left
19: right
30: far-right

If we assume that left hates right, and right hates left, the natural approval limit would be between the left wing and right wing parties. We would get mostly votes that rank only left wing or only right wing candidates. And the winner would be with good probability the far-left candidate, not the expected Condorcet winner (left).

The problem with "implicit approval cutoff after the ranked candidates" is that voters would be encouraged not to rank all the major candidates. Not good for Condorcet. That would remove some important information. In this example the sincere Condorcet winner could not be identified anymore.

> 46 A
> 44 B>C
> 10 C
> A>B 46-44 (margin=2)     B>C 44-10 (margin=34)   C>A 54-46 (margin=8)
> 
> Now Margins elects B,  rewarding the outrageous Burial strategy.
> 
> I can't tolerate any method that elects B in this scenario. Even assuming that all the votes are sincere,
> B is clearly the weakest candidate (the least "approved" and positionally dominated and pairwise-beaten
> by A.)
> 
Also here you assume that there is an implicit approval cutoff after the ranked candidates. What if the votes are sincere and there is no implicit approval cutoff?

Juho


P.S. I think the STV-BTR method that Robert proposed could make a lot of sense in societies where IRV way of thinking is strong.

P.P.S. Limiting the number of ranking levels or number of ranked candidates could make sense when the number of candidates is very high, or just to keep things simple for the vote counting process, or to keep things simple enough for the voters (not to frighten them with the idea of ranking all 100 candidates). I.e. not theoretically ideal, but in practical situations ranking some candidates may be much better than ranking only one, or not bothering to vote at all.
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