Definite Majority Choice: Difference between revisions

m
no edit summary
(HTML to wiki table using https://tools.wmflabs.org/magnustools/html2wiki.php)
mNo edit summary
 
(4 intermediate revisions by 4 users not shown)
Line 3:
See also [[Proposed Statutory Rules for DMC]].
 
It can be extended to use [[Range voting]] instead of [[Approval voting]] as its base: in that case, the method eliminates the least-rated candidate.
It can be thought of as a rated version of [[Benham's method]].
 
Its elimination logic is the same as [[Benham's method]], and the method can thus be thought of as a rated version of it.
 
== [[Range voting]] implementation ==
Line 37 ⟶ 39:
| 0 || 0 || 0 || 0 || 0 || 00
|}
 
== Alternative implementation ==
 
This implementation is called '''Pairwise Sorted Approval'''. It is the simplest of a class of [[Pairwise Sorted Methods]].
 
A voter ranks candidates, and specifies approval, either by using an [[Approval Cutoff]] or by ranking above and below a fixed approval cutoff rank.
 
To determine the winner,
# sort candidates in descending order of approval.
# For each candidate, move it higher in the list as long as it pairwise beats the next-higher candidate, and only after all candidates above it have moved upward as far as they can.
 
This procedure can be used to produce a social ordering. It finds the same winner as the Benham-form implementation.
 
== Properties ==
Line 46 ⟶ 60:
== Background ==
The name "DMC" was first suggested [http://lists.electorama.com/pipermail/election-methods-electorama.com/2005-March/015164.html here]. Equivalent methods have been suggested several times on the EM mailing list:
* The [[Pairwise Sorted Approval]] equivalentmethod/implementation was first proposed by [[Forest Simmons]] in [http://lists.electorama.com/pipermail/election-methods-electorama.com/2001-March/005448.html March 2001].
* The Ranked Approval Voting equivalentmethod/implementation was first proposed by [[Kevin Venzke]] in [http://lists.electorama.com/pipermail/election-methods-electorama.com/2003-September/010799.html September 2003]. The name was suggested by Russ Paielli in 2005.
 
The [http://lists.electorama.com/pipermail/election-methods-electorama.com/2005-March/015144.html philosophical basis] of DMC is to eliminate candidates that the voters strongly agree should ''not'' win, using two strong measures, and choose the undefeated candidate from those remaining.
Line 75 ⟶ 89:
 
== Example ==
Here's a set of preferences taken from Rob LeGrand's [https://www.csecs.wustlangelo.edu/~legrandrlegrand/rbvote/calc.html online voting calculator]. We indicate the approval cutoff using '''>>'''.
 
The ranked ballots:
Line 100 ⟶ 114:
! colspan=5 | against
|- align="center"
! class="against" | <span class="cand">Abby</span>
! class="against" | <span class="cand">Brad</span>
! class="against" | <span class="cand">Cora</span>
! class="against" | <span class="cand">Dave</span>
! class="against" | <span class="cand">Erin</span>
|- align="center"
! rowspan=5 | for
! class="for" | <span class="cand">Abby</span>
| bgcolor="yellow" | 645
| class="loss" | 458
Line 114 ⟶ 128:
| bgcolor="yellow" | 511
|- align="center"
! class="for" | <span class="cand">Brad</span>
| bgcolor="yellow" | 463
| bgcolor="yellow" | 410
Line 121 ⟶ 135:
| bgcolor="yellow" | 623
|- align="center"
! class="for" | <span class="cand">Cora</span>
| class="loss" | 460
| class="loss" | 460
Line 128 ⟶ 142:
| class="loss" | 460
|- align="center"
! class="for" | <span class="cand">Dave</span>
| class="loss" | 436
| bgcolor="yellow" | 609
Line 135 ⟶ 149:
| class="loss" | 311
|- align="center"
! class="for" | <span class="cand">Erin</span>
| class="loss" | 410
| class="loss" | 298
Line 152 ⟶ 166:
! colspan=5 | against
|- align="center"
! class="against" | <span class="cand">Erin</span>
! class="against" | <span class="cand">Abby</span>
! class="against" | <span class="cand">Cora</span>
! class="against" | <span class="cand">Brad</span>
! class="against" | <span class="cand">Dave</span>
|- align="center"
! rowspan=5 | for
! class="for" | <span class="cand">Erin</span>
| bgcolor="yellow" | 708
| class="loss" | 410
Line 166 ⟶ 180:
| bgcolor="yellow" | 610
|- align="center"
! class="for" | <span class="cand">Abby</span>
| bgcolor="yellow" | 511
| bgcolor="yellow" | 645
Line 173 ⟶ 187:
| bgcolor="yellow" | 485
|- align="center"
! class="for" | <span class="cand">Cora</span>
| class="loss" | 460
| class="loss" | 460
Line 180 ⟶ 194:
| class="loss" | 460
|- align="center"
! class="for" | <span class="cand">Brad</span>
| bgcolor="yellow" | 623
| bgcolor="yellow" | 463
Line 187 ⟶ 201:
| class="loss" | 312
|- align="center"
! class="for" | <span class="cand">Dave</span>
| class="loss" | 311
| class="loss" | 436
Line 319 ⟶ 333:
* [[Marginal Ranked Approval Voting]]: chooses the winner from a subset of the definite majority set.
 
[[Category:SingleCondorcet-winnercardinal votinghybrid methods]]
[[Category:Smith-efficient Condorcet methods]]
<!--
1,200

edits