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

Mon Mar 4 21:45:44 PST 2019

Robert,

I am strongly of the view that voters should be allowed to bullet-vote
or rank every single candidate or anything in between.

(For IRV and my suggested IRV-Condorcet hybrid I am opposed to allowing
above-bottom equal-ranking without a relatively complicated mechanism
I invented.)

> i think that it is reasonable for the law to assign a fixed number of 
> ranking levels, but it should be more than 3. 

What is "reasonable" about it?  There is no such restriction in 
elections for the President of Ireland or seats in
the legislature of the Australian state of New South Wales and other places.

> "..eliminating all-at-once all but the top two candidates."
>
> i dunno what that means.

In other words I support the Alternative Vote and not what is called the 
"Contingent Vote" or "Top-Two IRV".

https://en.wikipedia.org/wiki/Contingent_vote
> The contingent vote differs from thealternative vote 
> <https://en.wikipedia.org/wiki/Instant-runoff_voting>which allows for 
> many rounds of counting, eliminating only one weakest candidate each 
> round.

> 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.

> i still see no advantage of any method that is not Condorcet compliant 
> over one that is.

All Condorcet methods are vulnerable to Burial strategy and fail the 
Favorite Betrayal Criterion.

As has been pointed out to you on this list before, Margins is 
especially vulnerable to Burial.

Suppose sincere is:

46 A
44 B
10 C

I hope we are clear that if everyone bullet-votes like this then A is 
the Condorcet (and every other
type of) winner.

Supposing this scenario is accurately reflected in the pre-election 
polls, and so the B voters (perhaps
following advice from their party) decide "It looks like we are going to 
lose to A, maybe something good
will happen if we rank C" and so the votes cast are:

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.)

IRV and the IRV-Condorcet method I like elects A.

The Condorcet//Approval or Smith//Approval methods I like elect C.  The 
B voters "approved" C and they got C.

If you think it is "reasonable" to restrict the number of "ranking 
levels" and you want to allow voters to equal-rank
and presumably also skip ranking levels, then in my book you are talking 
about ratings rather than rankings
and you have something that stuffs up IRV or anything similar.

But it is fine for Condorcet//Approval or Smith//Approval or Smith//Top 
Ratings and several other voting methods
I like.

Chris Benham

On 5/03/2019 10:02 am, robert bristow-johnson wrote:
>
>
>
> ---------------------------- Original Message ----------------------------
> Subject: Re: [EM] The IRV-Disease has reached my town.
> From: "Chris Benham" <cbenhamau at yahoo.com.au>
> Date: Mon, March 4, 2019 7:41 am
> To: election-methods at lists.electorama.com
> --------------------------------------------------------------------------
>
> > I think voting reform activists in the US should welcome IRV and push to
> > make sure that there are
> > no abominable "details" like restricted ranking or eliminating
> > all-at-once all but the top two candidates.
>
> i dunno what that means.
>
> > Voters must be able to strictly rank from the top however many
> > candidates they wish, and the eliminations
> > must be one-at-a-time.
>
> then you need tougher ballot access restrictions.  SF had more than a 
> dozen candidates but only 3 levels of ranking.  i think that it is 
> reasonable for the law to assign a fixed number of ranking levels, but 
> it should be more than 3.  then the number of signatures required to 
> get a candidate's name on the ballot should be increased high enough 
> that *typically* the number of candidates is no more than the number 
> of ranking levels.  in Burlington Vermont, we had 5 levels and rarely 
> more than 5 candidates on the ballot for mayor.
>
> > In my judgement this is better than Approval  (or something
> > strategically equivalent that uses ratings ballots
> > with more than 2 slots) because it doesn't have any annoying defection
> > incentive and properly meets
> > "Mutual Relative Majority".
>
> the problem with both Approval and Score Voting is that the voter must 
> make a tactical decision about how high to score (or whether to 
> approve) their second-choice.  it is inherently flawed in that manner.
>
>
> > If  you are a fan of the Condorcet criterion, then I think it is fine to
> > modify IRV by before each elimination
> > we check for a Condorcet winner (among the so far remaining candidates)
> > and when we find one we stop
> > and declare that candidate the winner.
>
> one way to do this is STV-BTR  ("Bottom Two Runoff").  so it's just 
> like IRV, except when a candidate needs to be eliminated, it is not 
> simply the guy on the bottom (of first-choice votes), the two bottom 
> candidates are runoff against each other, counting only how voters 
> rank them relative to each other (like in the IRV final round), only 
> the winner of that Bottom Runoff advances to the next round.  this 
> STV-BTR is Condorcet compliant.
>
>
> > If you want something more simple then I think Condorcet//Approval is
> > acceptable.
> >
> > Voters simply rank the candidates they approve. Equal-ranking should
> > preferably be allowed.
>
> Yes!
>
> > A candidate that pairwise beats all the others wins. If there is no such
> > candidate then the most approved candidate wins.
>
> 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"?  that would change and 
> complicate the meaning of the ranked ballot.
>
>
> > A bit better, but equivalent in 3-candidate elections and harder to
> > explain, are Smith//Approval and (one of
> > my favourites) Max Covered Approval.
>
> i still think that Tideman RP using margins is the simplest meaningful 
> method that elects the same candidate that Schulze (based on margins) 
> elects when there are 3 in the Smith set.
>
> both the rules and meaning for marking the ballots (Ranking Candidate 
> A above Candidate B only means that if the election were held between 
> only those two candidates, your vote is for Candidate A) and the 
> decision algorithm (If more voters mark their ballots preferring 
> Candidate A over Candidate B than the number of voters marking their 
> ballots to the contrary, then Candidate B is not elected)m should be 
> simple for everyone to understand.  as simple as possible.
>
> i still see no advantage of any method that is not Condorcet compliant 
> over one that is.
>
> --
>
> r b-j                         rbj at audioimagination.com
>
> "Imagination is more important than knowledge."
>
>
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> Election-Methods mailing list - see https://electorama.com/em for list info

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