Majority Choice Approval: Difference between revisions
→How does it work?
Line 3:
== How does it work? ==
Voters rate candidates into a fixed number of rating
If one and only one candidate is
Unfortunately, unless there are many categories, and voters do not cluster at round numbers (e.g. multiples of 5 or 10), this procedure is likely to end up with multiple candidates reaching a majority at the same rating. Therefore, a tiebreaking procedure is needed. Some possible resolution methods include:
* MCA-A: Most approved candidate (most votes above lowest possible rating). This is also called "Majority Top//Approval", or MTA.
* MCA-P: Most preferred candidate (most votes at highest possible rating).
* MCA-M: Candidate with the highest score at the rating level where an absolute majority first appears
* MCA-S: [[Range voting|Range]] or Score winner.
* MCA-R: Runoff
** MCA-IR
** MCA-AR: Actual runoff: Voters return to the polls to choose one of the finalists. This has the advantage that one candidate is guaranteed to receive the absolute majority of the valid votes in the last round of voting of the system as a whole.
Line 29 ⟶ 27:
All MCA variants satisfy the [[Plurality criterion]], the [[Majority criterion for solid coalitions]], [[Monotonicity criterion|Monotonicity]] (for MCA-AR, assuming first- and second- round votes are consistent), and [[Minimal Defense criterion|Minimal Defense]] (which implies satisfaction of the [[Strong Defensive Strategy criterion]]).
All of the methods are [[Summability criterion|summable]] for counting at the precinct level. Only MCA-IR actually requires a matrix (or, possibly two counting rounds), and is thus "[[Summability criterion|summable for k=2]]"
The [[participation criterion]] and its stronger cousin the [[consistency criterion]], as well as the [[later-no-harm criterion]] are not satisfied by any MCA variant, although MCA-P only fails participation if the additional vote causes an approval majority.
Other criteria are satisfied by
* [[Independence of irrelevant alternatives]]
* The [[Condorcet criterion]] is satisfied by MCA-IR if the [[pairwise champion]] (aka CW) is visible on the ballots and would beat at least one other candidate by an absolute majority. It is satisfied by MCA-AR if at least half the voters at least approve the PC in the first round of voting. These methods also satisfy the [[Strategy-Free criterion]] if an SFC-compliant method such as [[Schulze]] is used to pick at least one of the finalists. All other MCA versions, however, fail the Condorcet and strategy-free criteria.
|