[EM] Poll on voting-systems, to inform voters in upcoming enactment-elections

[Kristofer Munsterhjelm]

On 2024-04-11 23:52, Richard, the VoteFair guy wrote:
> I suggest creating a list of links to the associated Wikipedia or 
> Electowiki articles, one for each method.  One person supplying all the 
> links will save time for the rest of us.  Personally I'm going to need 
> to read about some of these methods.

Good idea. Here are some links and brief descriptions. I've tried to be 
neutral; I may post later with my thoughts about the methods, and what 
notable criteria they pass and fail that I know of.

I've only done the methods that have a wiki page. At the bottom is a 
list of those methods that don't. Their proposers have already described 
them, but they might need a more clear description; in any case, I'll 
leave that to them :-)

Smith//Score:
	This is a composite method. https://electowiki.org/wiki/Composite_methods
	It takes rated ballots.
	It first eliminates every candidate not in the Smith set, and then does 
Range voting (Score voting) on the remaining candidates. No 
normalization is done after the elimination, so a vote A: 10, B: 7, C: 0 
still gives B 7 points and C 0 even if A isn't in the Smith set.
	In Daniel Carrera's words: "The ballot would look like a Score ballot. 
To process the ballots, the scores are converted into rankings (equal 
rankings allowed), and the highest scoring candidate inside the Smith 
set is elected." See also Toby's last post.

Approval with manual runoff:
	First do a round of Approval voting. Determine the top two candidates, 
then hold a later second round to determine who of the two wins. This is 
like STAR, but spacing the rounds apart makes it possible to hold 
debates, discuss the differences between the finalists, and so on. On 
the other hand, it's more expensive.

Smith//Approval (explicit - specified approval cutoff):
	This is a composite method. It takes a ranked ballot with an approval 
cutoff marked.
	Every voter approves of (gives a point to) every candidate ranked above 
his approval cutoff. The Smith set member with the most points wins.

Smith//Approval (implicit):
	Like Smith//Approval, except the voter can't specify an approval 
cutoff. Instead, every candidate ranked is counted as approved, and 
every candidate not ranked as not approved. The intent is to deter burial.

Woodall:
	https://electowiki.org/wiki/Woodall%27s_method
	This method takes ranked ballots. First make a note of the initial 
Smith set. Then keep doing IRV until only one candidate of the initial 
Smith set remains. Elect that candidate. Note: This is not Benham - the 
initial Smith set never changes.

Schwartz-Woodall:
	The same as Woodall, but with the Schwartz set. The Schwartz set is 
slightly less prone to ties.

Copeland//Borda:
	https://electowiki.org/wiki/Ranked_Robin
	This method takes ranked ballots.
	First eliminate every candidate not in the Copeland set. Then calculate 
the Borda scores of the remaining candidates and elect its winner. This 
can be done by using the Condorcet matrix alone.

Minmax(wv):
	https://electowiki.org/wiki/Minimax_Condorcet_method
	This method takes ranked ballots.
	Based on the ballots, consider each one-on-one matchups between 
candidates. Elect the candidate who has the most comfortable lead 
against the candidate who does best against him, one on one.

Plurality:
	You know this one. Choose-one ballots, equal rank not allowed, most 
first preferences wins.

Majority Judgement (category):
	https://en.wikipedia.org/wiki/Majority_judgment
	Various tiebreakers exist, e.g.
	 
https://en.wikipedia.org/wiki/Highest_median_voting_rules#Tiebreaking_procedures
	
	This takes graded ballots. The candidates give each candidate a grade, 
usually one of Excellent, Very Good, Good, Acceptable, Poor, or Reject. 
For each candidate, calculate the highest grade so that a majority gives 
that candidate at least that grade. The candidate with the highest such 
majority grade wins.
	The method is often indecisive, which means a tiebreaker has to be 
used. There are many, but they all try to preserve the dynamics of MJ.

IRV:
	https://en.wikipedia.org/wiki/Instant-runoff_voting
	This should also be familiar to everybody here. It takes ranked 
ballots. Repeatedly eliminate the Plurality loser until a candidate 
obtains a majority of the non-exhausted first preferences.

STAR:
	https://en.wikipedia.org/wiki/STAR_voting
	This takes rated ballots. The ballot typically has six ratings (zero to 
five inclusive), but the method could work with any number. The method 
counts the total number of points for each candidate. The pairwise 
winner of the two candidates with the most points wins.

Schulze:
	https://electowiki.org/wiki/Schulze_method
	This takes ranked ballots. The method is complex but basically amounts 
to a cloneproof Smith generalization of Minmax.
	Let a beatpath from a candidate A to another candidate Z be a series of 
pairwise defeats A beats B beats C beats... beats Y beats Z. The 
strength of the path is measured by the strength of its weakest 
individual pairwise contest. Let "the" beatpath from A to Z be the 
beatpath of strongest strength.
	The Schulze winner is the candidate whose beatpath to anybody else is 
at least as strong as their beatpath back to him.

Baldwin:
	https://electowiki.org/wiki/Baldwin%27s_method
	This takes ranked ballots.
	Baldwin is the Borda analog of IRV. In each round, the candidate with 
the lowest Borda count is eliminated. The last man standing wins. Also 
called Total Vote Runoff by Foley and Maskin.

Black:
	https://electowiki.org/wiki/Black%27s_method
	This takes ranked ballots.
	If there is a Condorcet winner, elect that CW. Otherwise elect the 
Borda winner.

Approval:
	https://electowiki.org/wiki/Approval_voting
	This takes an Approval ballot: vote for one or more. The candidate with 
the most marks wins.

Benham:
	https://electowiki.org/wiki/Benham%27s_method
	This method takes ranked ballots. Repeatedly eliminate the Plurality 
loser until there's a Condorcet winner among the remaining candidates. 
Elect the Condorcet winner when that happens.

Smith//DAC:
	This is a composite method. https://electowiki.org/wiki/Composite_methods
	https://electowiki.org/wiki/Descending_Acquiescing_Coalitions
	It takes ranked ballots.
	First eliminate every candidate not in the Smith set. Then perform the 
DAC algorithm to determine the winner.
	The DAC algorithm is complex, with the result being a cloneproof method 
otherwise close to Plurality.
	 Essentially, the DAC algorithm works like this: For each ballot, for 
each set of candidates a voter acquiesces to, increase that set's count 
by one. Then sort the sets in order of count, descending. Starting at 
the top with the current viable set being every candidate, eliminate 
from the viable set every candidate who is not in the set at the list's 
current position, unless that would eliminate everybody. The candidate/s 
remaining once you've traversed the whole list is/are the winner/s.
	A voter acquiesces to a set if he doesn't rank any candidate outside 
the set strictly above a candidate within the set.

RCIPE:
	https://electowiki.org/wiki/Ranked_Choice_Including_Pairwise_Elimination
	This takes ranked ballots.
	Modify IRV to, instead of eliminating the Plurality loser, eliminate 
the current Condorcet loser among the remaining (uneliminated) 
candidates. Only eliminate the Plurality loser if there is no Plurality 
loser. Once a candidate has a majority of the non-exhausted first 
preference votes, elect that candidate.

RP(wv):
	https://electowiki.org/wiki/Ranked_Pairs
	This takes ranked ballots.
	First count the pairwise matrix. Create a sorted list of every pairwise 
victory, sorted by its strength. Break ties by random ballot.
	Proceed from the top down the list, locking in a pairwise relation 
unless it would create a cycle.
	At the end, the locked-in contests give an order of candidates. This is 
the election order: the candidate on top is the winner.
	Strictly speaking, the tiebreaking is by random voter hierarchy, but 
I've skipped the details about how that is constructed.

I think that should be correct, but if I forgot something or described 
them incorrectly, let me know.

The methods not described are:
	Margins-Sorted Approval
	Double Defeat, Hare
	Margins-Sorted Minimum Losing Votes (equal-rated whole)
	Gross Loser Elimination
	Max Strength Transitive Beatpath

-km