Empathy List Archives

election-methods@mailman.electorama.com

Technical discussion of election methods

Fwd: Best IRV Tweak (correction)

Susan Simmons

Tue, Jul 6, 2021 7:17 PM

Sent from my MetroPCS 4G LTE Android Device

-------- Original message --------
From: Susan Simmons suzerainsimmons@outlook.com
Date: 7/6/21 12:14 PM (GMT-08:00)
To: Susan Simmons suzerainsimmons@outlook.com
Subject: Re: Best IRV Tweak (correction)

Pairwise support matrix (not pairwise win matrix)

To be definite, the jth entry in the ith row is the number of ballots on which candidate i is ranked ahead of candidate j.

Sent from my MetroPCS 4G LTE Android Device

-------- Original message --------
From: Susan Simmons suzerainsimmons@outlook.com
Date: 7/6/21 11:59 AM (GMT-08:00)
To: election-methods@lists.electorama.com
Subject: Best IRV Tweak

While there remains more than one uneliminated candidate eliminate the remaining one that is weakest relative to the other remaining candidates.

If "weakest" means least top support (relative to the other remaining candidates) then we have IRV.

But if we interpret "weakest" to mean the candidate with the fewest votes in any head-to-head contest (among the remaining candidates) then we have a Condorcet Compliant method.

In fact, the weakest candidate in this sense is a pairwise loser to its opponent in its worst head-to-head contest ... which could not happen to a Condorcet Candidate.

Operationally, this method is much simpler than IRV:

While the pairwise win matrix has more than one remaining entry, wipe out the row and column of the candidate whose row has the smallest remaining entry.

Under this simple method, would NYC still be bogged down in counting?

Sent from my MetroPCS 4G LTE Android Device

Sent from my MetroPCS 4G LTE Android Device -------- Original message -------- From: Susan Simmons <suzerainsimmons@outlook.com> Date: 7/6/21 12:14 PM (GMT-08:00) To: Susan Simmons <suzerainsimmons@outlook.com> Subject: Re: Best IRV Tweak (correction) Pairwise support matrix (not pairwise win matrix) To be definite, the jth entry in the ith row is the number of ballots on which candidate i is ranked ahead of candidate j. Sent from my MetroPCS 4G LTE Android Device -------- Original message -------- From: Susan Simmons <suzerainsimmons@outlook.com> Date: 7/6/21 11:59 AM (GMT-08:00) To: election-methods@lists.electorama.com Subject: Best IRV Tweak While there remains more than one uneliminated candidate eliminate the remaining one that is weakest relative to the other remaining candidates. If "weakest" means least top support (relative to the other remaining candidates) then we have IRV. But if we interpret "weakest" to mean the candidate with the fewest votes in any head-to-head contest (among the remaining candidates) then we have a Condorcet Compliant method. In fact, the weakest candidate in this sense is a pairwise loser to its opponent in its worst head-to-head contest ... which could not happen to a Condorcet Candidate. Operationally, this method is much simpler than IRV: While the pairwise win matrix has more than one remaining entry, wipe out the row and column of the candidate whose row has the smallest remaining entry. Under this simple method, would NYC still be bogged down in counting? Sent from my MetroPCS 4G LTE Android Device

robert bristow-johnson

Wed, Jul 7, 2021 2:48 AM

On 07/06/2021 3:17 PM Susan Simmons suzerainsimmons@outlook.com wrote:

Pairwise support matrix (not pairwise win matrix)

To be definite, the jth entry in the ith row is the number of ballots on which candidate i is ranked ahead of candidate j.

-------- Original message --------
From: Susan Simmons suzerainsimmons@outlook.com
Date: 7/6/21 11:59 AM (GMT-08:00)
To: election-methods@lists.electorama.com
Subject: Best IRV Tweak

While there remains more than one uneliminated candidate eliminate the remaining one that is weakest relative to the other remaining candidates.

If "weakest" means least top support (relative to the other remaining candidates) then we have IRV.

But if we interpret "weakest" to mean the candidate with the fewest votes in any head-to-head contest (among the remaining candidates) then we have a Condorcet Compliant method.

In fact, the weakest candidate in this sense is a pairwise loser to its opponent in its worst head-to-head contest ... which could not happen to a Condorcet Candidate.

Susan, as best as i can tell, this is exactly BTR-STV, which is what i am now trying to persuade the legislature of Vermont to adopt instead of Hare STV (which is the label i am using for what we often call "IRV"). See page 7 in this: https://drive.google.com/file/d/1hh0kWBn7LzxkHkJ_r6FsDyBNmnjC7x4o/view

so i agree that this is the best IRV tweek. it has a better chance of becoming law in my lifetime than either Schulze or Ranked-Pairs, which i think are superior RCV tabulation methods. but since they are all Condorcet compliant, the only way they can be practically better than BTR-STV is 1) any STV method can't have equal ranking on the ballot unless we put in fractional votes, and 2) Schulze and RP may deal with a cycle (which has never been known to happen in a government election) better than BTR.

so, for me, getting any Condorcet compliant method is better than holding out for the best Condorcet method.

Operationally, this method is much simpler than IRV:

only because of precinct summability. otherwise, it's more work than Hare STV.

r b-j . _ . _ . _ . _ rbj@audioimagination.com

"Imagination is more important than knowledge."

.
.
.

> On 07/06/2021 3:17 PM Susan Simmons <suzerainsimmons@outlook.com> wrote: > > > -------- Original message -------- > From: Susan Simmons <suzerainsimmons@outlook.com> > Date: 7/6/21 12:14 PM (GMT-08:00) > To: Susan Simmons <suzerainsimmons@outlook.com> > Subject: Re: Best IRV Tweak (correction) > > > Pairwise support matrix (not pairwise win matrix) > > > To be definite, the jth entry in the ith row is the number of ballots on which candidate i is ranked ahead of candidate j. > > > > -------- Original message -------- > From: Susan Simmons <suzerainsimmons@outlook.com> > Date: 7/6/21 11:59 AM (GMT-08:00) > To: election-methods@lists.electorama.com > Subject: Best IRV Tweak > > > > > While there remains more than one uneliminated candidate eliminate the remaining one that is weakest relative to the other remaining candidates. > > > If "weakest" means least top support (relative to the other remaining candidates) then we have IRV. > > > But if we interpret "weakest" to mean the candidate with the fewest votes in any head-to-head contest (among the remaining candidates) then we have a Condorcet Compliant method. > > > In fact, the weakest candidate in this sense is a pairwise loser to its opponent in its worst head-to-head contest ... which could not happen to a Condorcet Candidate. > Susan, as best as i can tell, this is exactly BTR-STV, which is what i am now trying to persuade the legislature of Vermont to adopt instead of Hare STV (which is the label i am using for what we often call "IRV"). See page 7 in this: https://drive.google.com/file/d/1hh0kWBn7LzxkHkJ_r6FsDyBNmnjC7x4o/view so i agree that this is the best IRV tweek. it has a better chance of becoming law in my lifetime than either Schulze or Ranked-Pairs, which i think are superior RCV tabulation methods. but since they are all Condorcet compliant, the only way they can be practically better than BTR-STV is 1) any STV method can't have equal ranking on the ballot unless we put in fractional votes, and 2) Schulze and RP may deal with a cycle (which has never been known to happen in a government election) better than BTR. so, for me, getting **any** Condorcet compliant method is better than holding out for the best Condorcet method. > > Operationally, this method is much simpler than IRV: > only because of precinct summability. otherwise, it's more work than Hare STV. -- r b-j . _ . _ . _ . _ rbj@audioimagination.com "Imagination is more important than knowledge." . . .