On Fri, Aug 28, 2009 at 11:08 PM, Kathy Dopp<kathy.d...@gmail.com> wrote: > Ralph, > > I think you've forgotten some crucially important points in your > explanation of how STV is counted. My comments below... > >> From: Raph Frank <raph...@gmail.com> >> Subject: [EM] Explaining PR-STV > >> PR-STV is based on 4 main principles >> >> 1) Each voter gets 1 vote and they can vote for any candidate they want. >> >> ** All votes are equal. ** > > To clarify, add.. > > "All votes are equal"... *if* they are counted but some voters' never > have their 2nd or 3rd choices counted at all or before their 2nd or > 3rd choice candidates are eliminated
I think we have a philosophical difference here (in fact, I know we do). You consider each individual ranking a vote. However, I don't look at it that way. Each voter has exactly 1 vote. This vote means that they can increase by 1 the vote total for any candidate. The ranks are not votes, they are just instructions to the counting official on how you want your vote handled. If a candidate is eliminated, you instruct the counter to move you vote to the next highest candidate who is still running. Similarly, if a candidate is elected, you instruct the counter to move the part of your vote that they don't need to the next preference. . > often *not true* but it is complex to explain how in STV a candidate > with more votes might be eliminated and a candidate with fewer votes > win instead due to nonmonotonicity which itself is due to the unequal > treatment of voters' votes whereby voters who support the least > popular candidates have the most say in which candidates are > eliminated, etc. It is true. You won't be eliminated unless you have the least number of votes at that point. >> 3) If you vote for a losing candidate, your vote is transferred to >> your next choice > > This is only true in special circumstances in STV/IRV, namely your > vote for a losing candidate is *only transferred to your next choice > **if** either: > > 1. your vote for a losing candidate occurs in early rounds so that > your next choice has not yet been eliminated, and > Fair enough, I should have said most preferred candidate who has not been eliminated or elected. > 2. your vote for a losing candidate is for a losing candidate who does > not lose in the final elimination round, in which case your later > choices will never be considered. Right, there is up to 1 Droop quota of voters who don't get represented. However, this is much better than potentially 49% of the voters not being represented in a single seat district. >> This reason for this rule is is so that you can safely give your first >> choice to your favourite even if he is a weak candidate. > > This is a wholly, entirely, deceptively false statement. In IRV/STV > your first choice vote can always hurt the chances of your 2nd choice > candidate winning. Mostly, I don't think non-monotonicity is an issue with PR-STV (or at least the benefits outweigh that disadvantage) Would you prefer the simple version where the 5 candidates who received the most votes in the first round win? That is monotonic, but is much less fair and gives more power to the parties. > Yes. this would be more accurately rephrased "Be careful to vote for a > very very weak candidate first if you do not want your later more > popular candidates to lose." Actually, one of the strategies for increasing the power of your vote is to vote for a weak candidate first. Your later more popular candidate will not be eliminated before a weaker but preferred candidate. >> 4) If you vote for a candidate who gets more votes than he needs, the >> surplus is transferred to your next choice. > > Again, this is only true in special situations similar to those > mentioned above for having your vote for a losing candidate > transferred. Ok, it is only transferred if you have indicated which candidate you want to transfer it to. I don't see how that is unreasonable. > You forget to mention that often STV can not fill all the seats unless > the quota is reduced to account for all the voters whose ballot > choices have been expired or eliminated so that many many voters in > STV are prohibited from participating in the final counting rounds. I don't think voters should be required to fill out all their rankings. If voters don't indicate a preference, then that is their choice. Having said that, I would support decreasing the quota on the fly. However, that is just making the method more complex for little benefit. > Hence any jurisdiction which has adopted STV have had to eliminate any > requirement for majority winners, etc. since the method most often > fails to find sufficient candidates that meet the quota. Well, the post is about PR-STV. I agree that in IRV, the disadvantages outweigh the benefits. However, the sheer power that PR-STV gives to the voters outweighs any disadvantages (and the disadvantages are lessened by it being multiseat anyway). It shifts power over candidate selection from party to the voters. > totally false statement depending on the definition of "strong". Well, in the context, I meant a candidate who easily reaches the quota (in the example, the candidate received double the quota). > There > are many examples where voters in STV are only allowed to have a vote > counted for one candidate even though they are supposed to be electing > a multi-seat *at-large* council, or where the *strong* candidate makes > it to the final counting round and then loses, where a *strong* > candidate (the first choice of *all* voters in a pairwise comparison) > is eliminated in an early round and a less *strong* candidate wins, > etc. etc. Well, the the single seat case, a "strong" candidate would be one who gets a majority of first preferences. ---- Election-Methods mailing list - see http://electorama.com/em for list info