[EM] Single Winner Systems categorization

[Dave Ketchum]

A few thoughts:

On Fri, 11 Jun 2004 16:21:36 -0500 Tom Ruen wrote:

> Below is my proposed categorization for the Wikipedia "Election system" page
> listing single winner systems.
> http://en.wikipedia.org/wiki/Voting_system#Single_Winner_Systems
> 
> My biggest change (from the current page) reclassifies "Yes/No Voting" into
> "One Choice voting", and moved Approval to the "Rated Value Voting"
> category.
> 
> 
> I hope my "One Choice Vote" category will be recognizes as unique, even if
> it doesn't offer all the fun games of more advanced methods.
> 
> I also removed the "tied-ranking" subcategory for Ranked Choice since I
> don't believe it is well defined which methods can allow tied rank ballots,
> and it may be equally undefined how such ballots will be counted.
> 
> Instead I added a subcategory "Sequential rounds" to connect methods that
> have sequential counting.
> 
> I was unsure about MCA under "Ratings" since it has no article written about
> it, but put it in a "Multiple round" category based on a one-line
> description.
> 
> Comments or suggestions are welcome.
> 
> Sincerely,
> Tom Ruen
> 
> P.S. I added a quick listing for those (nonparty vote) at the end under (B),
> but I'm less satisfied there, and I prefer "Majority/plurality" versus
> "SemiPR" versus "PR" as the broad categories.
> 
> ***********************
> (A) Single Winner Systems
> 
> Single Winner systems can be classified by how a vote is cast:
> 
>     1 '''One Choice Voting''' A valid vote offers a single most supported
> candidate.
>     2 '''Ranked choice Voting''' A valid vote can rank candidates 1,2,3...
> (Tied rankings may permitted in some methods)
>     3 '''Rated Value Voting''' A valid vote allows numerical
> values/categories to be associated with each candidate. Every candidate can
> be scored independent of the competition. (The set of valid
> values/categories is limited.)


Note that EM is getting invaded by methods that BOTH rank and rate.

> 
> They can also be classified on how many times votes can be counted. Methods
> like Plurality, Borda, and Approval with single counting rounds are simpler
> since voters can be sure to know how their votes will be applied.


"how many times votes can be counted"?  Is there less dangerous wording 
available?  I agree that we properly claim "one man one vote" - at least 
most of the time - but the "how many times" seems like an invitation to 
troublemakers.

> 
> 1. One Choice Voting methods
>     FPTP
>     Sequential rounds
>         Runoff voting
>         Elimination runoff
>         Exhaustive runoff
>     Random ballot
> 
> 2. Ranked Choice Voting methods
>     Borda count
>     Sequential rounds
>         Instant Runoff Voting/Alternative Vote/Preference voting (IRV)


While tied ranking can be considered, how to count such needs careful thought.


>             Supplementary Vote - reduced IRV process (2 rankings, 2 rounds)
>         Coombs' method
>         Bucklin voting
>     Condorcet method (Parallel pairwise rounds)


Here permitting tied ranking should be ENCOURAGED.  If two voters rank 
A=B, the effect should be the same as if one ranked A>B and the other 
ranked B>A.  Longer strings, such as A=B=C=D, do not introduce complexity, 
for Condorcet deals with one pair at a time.

What about skipping rank numbers?  I claim 1/2/2/9 is synonymous with 
1/2/2/3.  Could be a debate as to whether the skip should be permitted, 
but the counting should not be a problem.

Worth making the point that the ballots are the same as for IRV, and 
winners are the same most of the time (Condorcet has occasional cycles, 
and IRV is afflicted with occasional spoilers).


>         Ranked Pairs
>         Cloneproof Schwartz Sequential Dropping (CSSD)
>         Copeland's method
>         Ranked Majority Defeat Disqualification (DMDD)
> 
> 3. Rated Value Voting methods
>     Approval voting


Not much rating in Approval.


>     Cardinal Ratings (CR)
>     Multiple rounds:
>         Majority Choice Approval (MCA)
> .............................
> 
> QUICKLY CONSIDERED MULTIPLE WINNER METHODS
> 
> (B) Multiple Winner elections (not party-list)
>     One Vote per Winner (W votes)
>         Bloc voting/Plurality-at-large
>     Less than One Vote per Winner (<W votes)
>         Limited Voting (LV)
>     One Single Vote (1 vote)
>         Single Nontransferable Vote (SNTV)
>     One Distributed Vote (1 vote manually split among candididates)
>         Cumulative Voting (CV)
>         Equal&Even Cumulative Voting (E&E CV) - vote for N candidates, each
> gets 1/N votes.
>     Ranked Choice Voting (1 vote automatically split among candidates using
> rank ballot)
>         Single Transferable Vote (STV)

-- 
  davek at clarityconnect.com    people.clarityconnect.com/webpages3/davek
  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
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