Dear Richard, sorry for not getting to your reply earlier than now. Comments to your email in the text below.
2013/2/17 Richard Fobes <[email protected]>: > On 2/17/2013 12:17 AM, Peter Zbornik wrote: >> >> 2013/2/16 Kristofer Munsterhjelm<[email protected]>: >>> >>> On 02/14/2013 07:07 PM, Richard Fobes wrote: >>> ... >>>>> >>>>> ... as in >>>>> the top-down method of Otten? >>>> >>>> ... >>> >>> ... perhaps Peter meant this one? >>> http://www.votingmatters.org.uk/ISSUE13/P3.HTM >> >> >> yes, that's the method I was thinking of. Thanks Kristofer. > > > The approach specified in this article by Joseph Otten involves identifying > "doomed" candidates and "guarded" candidates. > > No, VoteFair representation ranking does not use that approach. > > VoteFair representation ranking uses a more advanced approach that looks > deeper into the ballots. > > Specifically, after the first-position winner has been chosen, VoteFair > _representation_ ranking starts by identifying the ballots that do not rank > that candidate as their first choice, and using those ballots it identifies > which (remaining) candidate is most popular. Then, it looks at the relative > ranking between those two candidates. > > Obviously the ballots that rank the first-position winner higher are > well-represented. The other ballots -- that rank the second tentatively > popular candidate above the first-position winner -- are not represented by > the first-position winner, so those ballots get full influence. The > well-represented ballots get only a small influence, specifically to the > extent that the first winner had the support of _more_ _than_ half the > voters (the amount beyond 50%). Then the second-position winner is > identified. I don't understand votefair ranking neither from the description above nor from the web pages. Don't you have a worked example and a complete and exhaustive description of the algorithm? > > Note that the second-position winner might be, or might not be, the > tentatively identified candidate. > > This approach precludes the strategy of a majority of voters putting > unpopular candidates at the top of their ballot (with different voters using > different unpopular candidates) as an attempt to fool the algorithm into > thinking they are not well-represented by the first-position winner. > > This approach avoids the weakness of STV (and IRV), which focuses attention > on the top-ranked candidate on each ballot, and only looking at lower-ranked > candidates on an as-needed basis. > > >>> Possibly combined in some way with >>> >>> http://www.votingmatters.org.uk/issue9/p5.htm . >>> >> >> Maybe, I don't know. > > > The key paragraph from this second article is: > > "Were we to know in advance that we would win, say, n seats in a region, > then it would be straightforward to use STV to select n candidates from the > potential candidates and put them in the top n places in our list. If we > don't know n in advance (which we don't!) then we can perform this operation > for every possible n, i.e. from 1 up to the number of seats available in the > region, and attempt to construct a list whose top n candidates are those > victorious in the nth selection ballot. (There is really only 1 ballot - the > division into n ballots is notional.)" > > It says what I said earlier: that STV needs to know in advance how many > seats will be won. > > I did not quickly understand how Joseph Otten proposes combining the > different lists (one for each value of "n") into a single list, and I'm not > in the academic world so I would not get paid to spend time figuring that > out, and since Peter says it may not be relevant, I'll leave this level of > detail unresolved. > > Getting to the point of answering Peter's question, no, VoteFair > representation ranking also does not use this second-article approach. > > Shifting perspective here, there is an important difference between STV and > VoteFair representation ranking. > > STV has the same weakness as IRV, namely it puts all of its focus on the > top-ranked candidate on each ballot. > > In contrast, VoteFair representation ranking looks much deeper into each > ballot to identify whether the ballot is from a voter who is (or is not) > well-represented by which candidates have won the earlier seats (in the > party list). Well I don't understand what "looking deeper" means. > > As I've indicated before, if a party list needs to be longer than about five > positions, it's possible to get even better proportionality in the later > seats by using an algorithm used in VoteFair _negotiation_ ranking. > > The algorithm behind VoteFair _negotiation_ ranking could calculate a full > party-list ranking, and then if the ranking violates the gender-based rules, > then an administrator can indicate an "incompatibility" that adjusts the > ranking to meet the gender-based quota (expressed as an incompatibility). > > There are two reasons why I haven't proposed using VoteFair negotiation > ranking for use in a party-list election: > > * It is not designed to handle thousands of voters, which would be needed > for party-list voting. (It's designed for a group of people working in a > collaborative situation.) Party list voting will have max 500 voters, typically less than 100. > > * It is designed in a way that regards the different party-list positions as > distinct "proposals" (such as filling cabinet positions) rather than as > somewhat-equivalent seats being filled. > > Yet, as I've indicated, the advanced adjustment capabilities of VoteFair > _negotiation_ ranking can be combined with VoteFair _representation_ > ranking. That would create a "VoteFair party-list ranking" algorithm. > > However, combined with the need for gender adjustments in up to two > positions, that algorithm would only start having significantly different > results starting at about the fifth seat. That makes it not worthwhile for > this situation that involves five seats, with a high likelihood that the > fifth-position winner will be displaced to fulfill a gender-based quota > requirement. As I mentioned, I am looking for an algorithm, which allows qouted seats to be proportionally distributed, in order to avoid that the same voters get all quoted seats. > > In the future when longer party lists are needed, adjustments can be made > starting at about the fifth seat to provide representation for small -- > although not tiny -- minorities. > > If we expect the party to win only 1, 2, 3, 4, or 5 seats, the first four > positions need to be filled by: > > 1: The overall most popular "majority" candidate > > 2: The overall most popular "opposition" candidate > > 3: The next-most popular "majority" candidate > > 4: The next-most popular "opposition" candidate > > That's what VoteFair representation ranking calculates -- in a way that > deeply looks into the ballots to ensure representation for > not-yet-represented voters. > > Richard Fobes > Best regards Peter Zborník ---- Election-Methods mailing list - see http://electorama.com/em for list info
