[EM] Anyone got a good analysis on limitations of approval and range voting?
It seems to me that approval and range voting eliminate most of the strategic opportunity in single winner elections and the marginal improvement of other methods is fairly small. Can anyone point me to analysis, preferably at a layman level, that contradicts or supports this assertion? Or, in succinct terms, what are the strategic flaws in approval or range voting? Thanks, Matt -=- Election-Methods mailing list - see http://electorama.com/em for list info
Re: [EM] Anyone got a good analysis on limitations of approval and range voting?
On Nov 7, 2009, at 3:12 PM, Matthew Welland wrote: It seems to me that approval and range voting eliminate most of the strategic opportunity in single winner elections and the marginal improvement of other methods is fairly small. Can anyone point me to analysis, preferably at a layman level, that contradicts or supports this assertion? Or, in succinct terms, what are the strategic flaws in approval or range voting? this is no published analysis, but it should qualify as layman level. this is why i don't like either approval or range voting in a governmental election. in a sentence: Approval Voting does not collect enough information from voters and Range Voting requires too much. since any of these methods we discuss here really exist for the purpose of dealing with more than two candidates (if there are exactly two candidates no one really disagrees about what to do) let's see if we have to do with multiple candidates. in fact we can use the 2009 mayoral election in Burlington VT as an object lesson. we have Candidate A (we'll call Andy), Candidate B (we'll call Bob), Candidate C (we'll call Curtis, but in Burlington his name was Kurt), and candidate D (we'll call Dan). Approval Voting: so i approve of Andy and Bob, maybe Dan (not likely) and definitely not Kurt (err Curtis, candidate C). but, if the election comes down to Andy vs. Bob, i want to register my preference for Andy. how do i do that? so then i'm thinking (tactically) that the Bob supporters aren't gonna be reciprocating with an approval vote for Andy, so what do i do if i really support Andy, am willing to settle for Bob, but really want Andy. i will agonize over the decision and likely just vote approval for Andy, just like i would in a traditional FPTP election. but then there is no information coming from me that i prefer Bob a helluva lot more than i approve of Curtis. so Approval Voting has not relieved me, as a voter, from the need to consider tactics, if i want my vote to be effective. Range Voting: so i have 100 points that i can distribute among the 4 candidates. well definitely Candidate C (Curtis, really Kurt) gets zero of my points. i might toss Dan 5 points, but i would likely not waste them. so how do i divide my points between Andy and Bob? i like them both, but prefer Andy over Bob, so what do i do? i have to think tactically again. are the Bob supporters gonna be tossing any points to Andy? i can't trust that they will, they will probably just put all of their support for the candidate that they are behind. if i want my vote to compete effectively with theirs, i will end up putting all 100 points behind my candidate Andy. so, if we have any political identification at all, my vote under Range will convey no more information than it would with FPTP. IRV, Condorcet, and Borda, use the simple ranked-order ballot where we say who we support first (candidate A for me), who is our second choice (candidate B), who is our third choice (candidate D for me) and who is our last choice (candidate C for me). so if the election was just between A and B, we know that this voter (me) would vote for A. if the election was just between B and D, we know this voter would vote for B. if the election was between C and D, we know this voter would choose D. of course, for a single voter (not necessarily for the aggregation of votes) there is no circular preference, we know that if the election was between A and D, this voter would vote for A. we know that this voter would vote for B if the election was between B and C. and we know that this voter would vote for A if it were between A and C. from that simple ranked-order ballot, we know how the voter would vote between any selected pair of candidates in the hypothetical two-candidate election between those two. of course IRV, Condorcet, and Borda use different methods to tabulate the votes and select the winner and my opinion is that IRV (asset voting, i might call it commodity voting: your vote is a commodity that you transfer according to your preferences) is a kabuki dance of transferred votes. and there is an *arbitrary* evaluation in the elimination of candidates in the IRV rounds: 2nd- choice votes don't count for shit in deciding who to eliminate (who decided that? 2nd-choice votes are as good as last-choice? under what meaningful and consistent philosophy was that decided?), then when your candidate is eliminated your 2nd-choice vote counts as much as your 1st-choice. i don't like Borda because it has another arbitrary valuation. the difference in score between your 1st and 2nd choice is the same as the difference in score between your 2nd and 3rd choice. but what eternal value is that based on? what if i like my 1st and 2nd choice almost equally, but think my 3rd choice is a piece of crap? (this is what Range
Re: [EM] Anyone got a good analysis on limitations of approval and range voting?
On Sat, Nov 7, 2009 at 8:12 PM, Matthew Welland m...@kiatoa.com wrote: It seems to me that approval and range voting eliminate most of the strategic opportunity in single winner elections and the marginal improvement of other methods is fairly small. The recommended strategy in approval is to approve one of the top 2 and also any other candidates who are above your approval threshold. The threshold is not so important, as it is likely that one of the top 2 will win, so that approval is the only one that matters. You should approve all you prefer to the best of the top 2 and should never approve someone you like less than the worst of the top-2. Some possible thresholds - approve all you prefer to the expected winner - approve all you prefer to the expected utility of the election - approve all you prefer to the best of the top 2 - approve all you prefer to the worst of the top 2 I prefer to the first first one as it will results in the condorcet winner winning the election if there are accurate polls. As long as voters know who are the contenders, then approval strategy is pretty easy. Where there are 3 contenders, there is still some issue with regard to handling the middle candidate. The voter would need to make a call about which tie was more likely and also the differences in utility. Also, strategy isn't necessarily a bad thing. The problem with plurality is that it converges on the 2 party system. It is a Nash equilibrium. If you could go through each voter after an election and ask them if they want to change their vote, most of them wouldn't. It would normally just reduce the margin or victory for their favourite of the top-2. However, with approval, you can have a sequence that goes like: A and B are the top 2, but C is the condorcet winning candidate. Voters follow the policy that they will approve one of the top 2 and any candidate they prefer to the expected winner. Since every voter will only vote for one of A and B (since they are the top-2), one of them must end up with less than 50% of the vote. C is the condorcet winner, so he is preferred to whoever is the expected winner by at least half of the voters. Thus the first poll will show something like A: 45 B: 55 C: 51 Thus C will suddenly be one of the top-2. This might take a few polls, but as C gets more press reports, his percentage will increase. Once he is one of the top-2, he cannot be displaced. No matter who is the other one, he will be preferred to that candidate by more than 50%. Also, once he is one of the top 2, any voters who prefer him to all other candidates will suddenly stop approving either of A or B. Thus one of them will drop in popularity. The point is that it isn't strategy that is the problem. It is that strategy results in the voters ending up with the the better of 2 evils. With approval, the result is that a condorcet winner should normally win, so any strategy results in a fair result. Election-Methods mailing list - see http://electorama.com/em for list info
Re: [EM] Anyone got a good analysis on limitations of approval and range voting?
Raph Frank wrote: On Sat, Nov 7, 2009 at 8:12 PM, Matthew Welland m...@kiatoa.com wrote: It seems to me that approval and range voting eliminate most of the strategic opportunity in single winner elections and the marginal improvement of other methods is fairly small. The recommended strategy in approval is to approve one of the top 2 and also any other candidates who are above your approval threshold. That's strategy T. Some times (see Rob LeGrand's dissertation defense slides) a strategy A is better: approve all that you like better than whoever's getting the most Plurality votes, and approve of him as well if you prefer him to the one in second place on the Plurality count. (I think it's a Plurality count. Late here, so vote-getter may refer to Approval votes - I'm not sure.) Election-Methods mailing list - see http://electorama.com/em for list info
Re: [EM] Anyone got a good analysis on limitations of approval and range voting?
On Sat, Nov 7, 2009 at 10:57 PM, Kristofer Munsterhjelm km-el...@broadpark.no wrote: The recommended strategy in approval is to approve one of the top 2 and also any other candidates who are above your approval threshold. That's strategy T. Some times (see Rob LeGrand's dissertation defense slides) a strategy A is better: approve all that you like better than whoever's getting the most Plurality votes, and approve of him as well if you prefer him to the one in second place on the Plurality count. Strategy A, as you defined it, is almost equivalent to just setting the threshold to the utility of the expected winner. (I think it's a Plurality count. Late here, so vote-getter may refer to Approval votes - I'm not sure.) I don't think that actually matters much. They should be roughly the same. The main point is that the top-2 candidates are the 2 candidates who are most likely to tie, so you should approve one of them and not the other. Election-Methods mailing list - see http://electorama.com/em for list info
[EM] Anyone got a good analysis on limitations of approval and range voting?
It seems to me that approval and range voting eliminate most of the strategic opportunity in single winner elections and the marginal improvement of other methods is fairly small. Can anyone point me to analysis, preferably at a layman level, that contradicts or supports this assertion? Or, in succinct terms, what are the strategic flaws in approval or range voting? Thanks, Matthew Welland --well... there is the whole rangevoting.org website... my more-recent papers at math.temple.edu/~wds/homepage/works.html discuss range voting including some ways it is provably better than every rank-order voting system for either honest or strategic voters... --but those are not exactly succinct... OK Let me try: 1. Range for 100% honest voters behaves better than IRV, Borda, Condorcet and it is pretty intuitively clear why -- strength of preference info used, not discarded. 2. For 100% strategic voters Borda is a total disaster as is also pretty obvious... far worse than approval voting... but range voting just degenerates basically to approval voting, which still works pretty well since, e.g. it obeys the favorite betrayal criterion. If the strategic voters use I'll exaggerate on the top two naive strategy (which in fact, in the real world, they pretty much do) then Condorcet and IRV both degenerate to strategic plurality voting, which is pretty obviously worse than approval voting, so range beats them. For Condorcet systems with ranking-equalities allowed, they might behave better with strategic voters, though. I've posted on that topic before. 3. The main perceived flaw in range voting is for strategic+honest voter MIXTURES and under the worrying assumption that who decides to be strategic, is CORRELATED with the politics of that voter. Thus for example, strategic Bush voters could beat unstrategic Gore voters. Problem isn't really much of a problem if the Bush strategy-fraction is the same as the Gore strategy fraction (a claim backed up by computer sims). It is only if they differ. 4. I'm unaware of any evidence from the real world that Bushy and Gorey voters really are any different strategically with range voting. However, there is evidence that Nader voters are less strategic and more honest. (Not surprisingly since voting Nader in the USA *was* unstrategic.) However, the evidence from the real world is that all political types of range voters are substantially honest, i.e.only a small fraction vote approval-style, and this causes Nader, despite this relative disadvantage, to do a lot better with range voting than he does with approval voting. -- Warren D. Smith http://RangeVoting.org -- add your endorsement (by clicking endorse as 1st step) and math.temple.edu/~wds/homepage/works.html Election-Methods mailing list - see http://electorama.com/em for list info
Re: [EM] (no subject)
On Nov 2, 2009, at 12:57 PM, Juho wrote: Ok, these examples are sort of second level behind the hottest political arena. It makes sense not to involve party politics e.g. in decision making in the schools. Are there maybe counties/cities where the primary decision making body would have remained non- partisan? In California, my sense is that most city elections and some county elections are in fact (not just nominally) non-partisan. That's not true for larger cities and counties, where the nominally non-partisan seats tend to be the farm team for the major parties--it's how you get on the ladder to the show. Juho On Nov 2, 2009, at 4:40 PM, Jonathan Lundell wrote: On Nov 1, 2009, at 10:49 PM, Juho wrote: Firstly, STV-PR can be used in all public elections, including those that are non-partisan. Yes. Non-partisan multi-winner elections are however rare in politics. They may be more common e.g. when electing only a small number of representatives within a small community. Non-partisan multi-seat bodies compose the overwhelming majority of elected offices in California. All our local boards (county and city governing board, school boards, fire protection and sanitation districts) are elected this way, and would be prime candidates for STV. My sense is that this is fairly common across the US, though in some states some of these offices are partisan. There's plenty of scope for non-partisan PR. Election-Methods mailing list - see http://electorama.com/em for list info Election-Methods mailing list - see http://electorama.com/em for list info
