[EM] Burlington VT reconsidering IRV 10 years after IRV failed to elect the Condorcet Winner

Wed Dec 4 13:01:27 PST 2019

On 12/4/2019 12:18 AM, robert bristow-johnson wrote:
 > How does this look to you guys?  ...

Item 4 needs some serious surgery.  It needs to be split into two or 
even three parts, which I'll refer to here as 4a and 4b and 4c.

Notice that there is no provision for how to count a ballot on which the 
voter ranks more than one candidate at the same preference level!  To 
fix this serious unfairness I suggest the following wording for 4a 
(which uses the same first sentence):

4a: In each round, each voter’s ballot shall count as a single vote for 
whichever remaining candidate the voter has ranked highest. If a voter 
ranks two or more remaining candidates at the same currently-highest 
preference level then that single vote shall be split into equal-weight 
two-digit decimal numbers that add up to no more than a single vote. 
Specifically if a ballot ranks three remaining candidates at the same 
currently-highest preference level then each of those three candidates 
will each receive 0.33 portion of a vote during the current round.

(Grammar: "currently-highest" would not normally use a hyphen because of 
the "ly" ending, but including the hyphen makes the meaning less 
ambiguous in this legal usage.)

The remaining portion of item four could be used for item 4b, BUT please 
consider the following fairer wordings for items 4b and 4c, which might 
be as easy to understand as the existing wording:

4b: In each elimination round each remaining candidate is compared to 
each other remaining candidate one pair at a time to determine whether 
there is a "pairwise-losing" candidate that is ranked lower on more than 
half the ballots in each and every pairwise comparison. If there is a 
pairwise-losing candidate who loses all its pairwise contests against 
all the other remaining candidates then that candidate is eliminated.

4c: If an elimination round has no pairwise-losing candidate then the 
candidate who receives the fewest votes is eliminated in that round. If 
there is a tie for fewest votes and the tie affects which candidate can 
win, then a recount shall be done and if the recount also results in a 
tie that affects who wins then a court shall determine how to resolve 
the tie.

The longer wording for 4c is needed because the current wording fails to 
explain how to resolve an IRV tie.

The method described above is NOT Condorcet compliant, but it is so 
close to being Condorcet compliant that any exception would also involve 
bigger unfairness issues (such as a very small turnout).

Regardless of whether you can use the recommended pairwise wording, at 
least make sure that the wording explains what to do when a voter ranks 
more than one candidate at the same preference level.  Note that tossing 
out that ballot is NOT a valid option!  If someone in your group insists 
that it should be tossed out, then at least stop ignoring the ballot 
when there is a round in which only one "remaining" candidate is ranked 
at that same preference level.

Good luck!  You're doing great work!!!

Richard Fobes

On 12/4/2019 12:18 AM, robert bristow-johnson wrote:
>
> How does this look to you guys?  This is the original language on the existing resolution to implement RCV that is not Condorcet compliant:
>
> ________________________________________________________
>
>
> All elections of mayor, city councilors and school commissioners shall be by ballot, using a system of ranked choice voting without a separate runoff election. The chief administrative officer shall implement a ranked choice voting protocol according to these guidelines:
>   (1) The ballot shall give voters the option of ranking candidates in order of preference.
>   (2) If a candidate receives a majority (over 50 percent) of first preferences, that candidate is elected.
>   (3) If no candidate receives a majority of first preferences, an instant runoff re-tabulation shall be performed by the presiding election officer. The instant runoff re-tabulation shall be conducted in rounds. In each round, each voter’s ballot shall count as a single vote for whichever continuing candidate the voter has ranked highest. The candidate with the fewest votes after each round shall be eliminated until only two candidates remain, with the candidate then receiving the greatest number of votes being elected.
>   (4) The city council may adopt additional regulations consistent with this subsection to implement these standards.
>
> ________________________________________________________
>
>
> and here is the original languate modified to implement BTR-STV that is Condorcet compliant:
>
>
> ________________________________________________________
>
>
> All elections of mayor, city councilors and school commissioners shall be by ballot, using a system of ranked choice voting without a separate runoff election. The chief administrative officer shall implement a ranked choice voting protocol according to these guidelines:
>   (1) The ballot shall give voters the option of ranking candidates in order of preference.
>   (2) If a candidate receives a majority (over 50 percent) of first preferences, that candidate is elected.
>   (3) If no candidate receives a majority of first preferences, an instant runoff re-tabulation shall be performed by the presiding election officer. The instant runoff re-tabulation shall be conducted in sequential rounds. A "remaining candidate" is defined as a candidate that has not been eliminated in any previous round. Initially, no candidate is eliminated and all candidates begin as remaining candidates.
>   (4) In each round, each voter’s ballot shall count as a single vote for whichever remaining candidate the voter has ranked highest. The two candidates with the fewest votes in a round, herein designated as "A" and "B", shall be compared in a runoff in which the candidate, A or B, with lesser voter support is eliminated in the same round. If the number of ballots having A ranked higher than B exceeds the number of ballots having B ranked higher than A, then B has lesser voter support, B is eliminated, and A remains for the following round. Likewise, if the number of ballots having B ranked higher than A exceeds the number of ballots having A ranked higher than B, then A has lesser voter support, A is eliminated, and B remains for the following round. In the case that the aforementioned measure of voter support between A and B is tied, then the candidate with fewest votes is eliminated in the same round.
>   (5) This runoff re-tabulation, eliminating one candidate each round, is repeated until only two candidates remain, with the candidate then receiving the greatest number of votes being elected.
>   (6) The city council may adopt additional regulations consistent with this subsection to implement these standards.
>
> ________________________________________________________
>
>
> Is this good language for BTR-STV?  Can any of you think of a hole in this description?  Can any of you make it better or more concise?
>
> Thank you.
>
> r b-j
>
>
>> On December 3, 2019 3:44 PM Kristofer Munsterhjelm <km_elmet at t-online.de> wrote:
>>
>>
>> On 03/12/2019 16.54, robert bristow-johnson wrote:
>>>
> ...
>>>
>>> I want to figure out some good language to change this from regular-old IRV to Bottom-Two Runoff, Single Transferable Vote, BTR-STV .  If someone is good at writing legal language or if this BTR-STV has had legislative language written for it somewhere else, I would like to see it.
>>>
>>> The language that needs to be changed, to make this RCV Condorcet-compliant is:
>>>
>>> "... The candidate with the fewest votes after each round shall be eliminated ..."
>>>
>>> How can we clearly and concisely change that to Bottom-Two Runoff?
>>
>> My first stab would be: "After each round, of the two candidates with
>> the fewest votes, the candidate ranked below the other by the most
>> voters shall be eliminated".
>>
>> Alternatively "on the most ballots". Or "among the two candidates". Or
>> "of the two candidates with the fewest votes in that round".
>>
>> Presumably there has to be some tie-breaking language for the case where
>> more than one candidate is last or next-to-last. But I suppose there is
>> some similar language for IRV as is.
>>
>> If there is no equal-rank or truncation, you can also say "the candidate
>> ranked below the other by a majority of the voters".
>>
>> The strategy to turn IRV into BTR-IRV is probably the best one. Woodall
>> is better than BTR-IRV, and you could turn the method into Woodall by
>> checking for a CW before a round starts, but then you'd have to define
>> what a CW means in a way that doesn't confuse people who are unfamiliar
>> with Condorcet.
>>
>> Looking again at the language, point (3) is already rather convoluted.
>> Perhaps it would be better to split up the definition. Something like:
>>
>> (3) If no candidate receives a majority of first preferences, an instant
>> runoff re-tabulation shall be performed by the presiding election
>> officer. The instant runoff re-tabulation shall be conducted in rounds.
>> In each round, each voter’s ballot shall count as a single vote for
>> whichever continuing candidate the voter has ranked highest, and
>> subsidiarily to determine what candidate to eliminate. After each round,
>> the two candidates with the fewest votes shall be considered for
>> elimination. Of these two candidates, the candidate ranked below the
>> other by the most voters shall be eliminated in that round. The counting
>> in rounds shall continue until only two candidates remain, with the
>> candidate then receiving the greatest number of votes being elected.
>>
>> (Maybe also call it something else than "instant runoff re-tabulation"
>> because it's no longer IRV, but I can't think of a better name at the
>> moment.)
>>
>> I'm much less certain about Woodall. See below for something I cooked up.
>>
>> (1) The ballot shall give voters the option of ranking candidates in
>> order of preference.
>> (2) If a candidate receives a majority (over 50 percent) of first
>> preferences, that candidate is elected.
>> (3) If no candidate receives a majority of first preferences, an instant
>> runoff re-tabulation shall be performed by the presiding election
>> officer. The instant runoff re-tabulation shall be conducted in rounds,
>> for which the counting shall be conducted according to the following
>> three points.
>> (4) If there exists a continuing candidate so that for every other
>> continuing candidate, the former candidate is ranked ahead of the latter
>> by a majority of the voters, the former candidate is elected.
>> (5) If there is no such candidate, each voter’s ballot shall count as a
>> single vote for whichever continuing candidate the voter has ranked
>> highest. The candidate with the fewest votes shall be eliminated, which
>> marks the end of the current round and the beginning of the next.
>> (6) The counting in rounds shall continue until a candidate is elected
>> or only one candidate remains, with the remaining candidate then being
>> elected.
>> (7) The city council may adopt additional regulations consistent with
>> this subsection to implement these standards.
>>
>> (Strictly speaking, the latter half of point 6 is redundant because when
>> only two candidates remain, the winner beats the loser pairwise and
>> would be elected by point 4. But a potentially infinite loop looks more
>> dangerous than a finite one.)
>>
>> I haven't written legislative language before, but maybe it can serve as
>> a starting point for others who have.
>>
>> -km
>
> --
>
> r b-j                  rbj at audioimagination.com
>
> "Imagination is more important than knowledge."
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