Single transferable vote: Difference between revisions

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*Giving one vote to one of the top-ranked candidates, and giving no vote to the other top-ranked candidates (likely best done by choosing randomly which top-ranked candidate gets the vote)
* ER-IRV (fractional): Counting a ballot with N top-ranked candidates as 1/N of a vote for each candidate.
* ER-IRV (whole votes) or Approval-IRV: Giving one vote to each equally-top-ranked candidate. Can optionally be combined with a suggestion that ballots that equally rank candidates shouldn't be able to prevent the elimination of those candidates.<ref name="reddit 2011">{{cite web | title=Proportionality failure in STV with equal-ranks with whole votes : EndFPTP | website=reddit | date=2019-12-05 | url=https://www.reddit.com/r/EndFPTP/comments/e6bt6s/proportionality_failure_in_stv_with_equalranks/f9thuy4/?context=8&depth=9 | access-date=2020-02-10}}</ref>
 
The nature of IRV is such that many of its derived properties depend on each voter exerting influence such that their support for all candidates adds up to at most "one vote" (see [[:Category:FPTP-based voting methods|Category:FPTP-based voting methods]]). Thus, fractional equal-ranking preserves most of IRV's criterion compliances and properties, but not Approval-IRV. In addition, fractional equal-ranking creates less ambiguity around how to configure the IRV rules, whereas with Approval-IRV, different variations of the rules which would give the same results with other forms of IRV can give different results:
 
Note that in the single-winner case, giving a vote to each equally-top ranked candidate can lead to different results when using either the "if in any round any candidate gets a quota (if using a Droop quota, a majority, in the single-winner case) they win" rule or the "all but ((number of winners) + 1) candidates must be eliminated, with the (number of winners) candidate(s) with the most votes then winning" rule (which can also be thought of as "all but (number of winners) candidates must be eliminated, with the remaining candidate(s) winning"). Single-winner example: <blockquote>45 A=C>B