Posts by Steve Todd
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Legal Beagle: Voting in an STV election, in reply to Tim McKenzie,
But given the choice, would “ordinary people” prefer that votes belong to candidates, or that votes belong to voters?
I’ve no idea what other people think, but, in my view, votes belong to the voters, which they give *for* candidates, not *to* candidates.
In that case, your claim that “There is no incentive for a voter to vote in any way other than according to his or her actual preference” is false in many, many more situations, and this is trivial for individual voters to exploit. It’s called free-riding.
I’m very aware of “free riding”, have been since 1995. Markus has written about it here – I’ve read this particular article many times: http://www.votingmatters.org.uk/ISSUE18/INDEX.HTM (again, scroll down to Papers with citations, 2. M. Schulze: Free riding, then click on (p2-8, PDF 48Kb) ).
NZ STV undermines / nullifies Woodall free riding, the ploy adopted by some voters of giving their first preference for a weak candidate, in anticipation of him or her being excluded and their vote being transferred at full value (often jumping over an already-elected candidate, or candidates).
You were referring to Hylland free riding, a ploy that, after the fact, cannot be shown to have occurred “simply from the ballot data”.
Markus tried to find evidence of Woodall free riders in Cambridge MA council elections in 1999 and 2001, but couldn’t. In his Summary, he gives a number of possible reasons for this. I see no reason why these explanations could not apply to potential Hylland free riders, as well.
My point is, most people (who vote) consider voting, particularly in important, public, elections, to be an important civic act. That being the case, they have no wish to mess about with their vote, especially when the outcome they might hope to help bring about, is in no way guaranteed, and could indeed backfire on them badly.
So, I say again – in the real world of real people voting in real elections – there “is no incentive to vote in any way other than according to […] actual preference[s]”. In the academic world of social choice theory, you might well consider that to be wrong, but in actual practice, it is not – in my view.
Having said that, of course there will be some voters who will try it on, but, in real, public, elections, there is never enough of them (knowingly acting in concert) to effect the outcome they want.
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Legal Beagle: Voting in an STV election, in reply to Tim McKenzie,
I have now had a chance to read through the posts you put up on Friday afternoon. I think it’s fairly clear that our toing and froing is turning people off, and that we are starting to repeat ourselves. Nevertheless, you have made some comments that I must respond to.
In contrast, the Schulze method copes perfectly well with giving equal preference to multiple candidates.
Does it now?
I have read this: https://en.wikipedia.org/wiki/Schulze_method , and, for the umpteenth time now, this: http://www.votingmatters.org.uk/ISSUE17/INDEX.HTM (scroll down to Papers with citations, 3. M. Schulze, etc., then click on (p9-19, PDF 76Kb) ).
(I used to subscribe to 'Voting matters', receiving it in hard copy format, before it was put up online.)
It is very clear to me that single-winner Schulze STV is not programmed to allow voters to express equality of preference (EQP).
As I have stated, and, I believe, demonstrated, Meek STV (NZ STV), is very straightforward – tedious, yes, but easy to program (for computer programmers), and not difficult to follow for ordinary people.
In contrast, it is also very clear to me that Schulze STV must indeed be extremely tedious to program. To produce a program that also allows for EQP would surely be a nightmare (particularly for his multi-seat version, which, even now, I’m not sure has been perfected). Therefore, prima facie, your statement, above, is almost certainly false (at least for the time being). Indeed, despite your confident assertion, EQP might well turn out to be too difficult to program in Schulze, particularly in the multi-seat case.
David Hill (and no doubt others), has produced an EQP STV program (for both single- and multi-seat elections). His overall STV computer program is a demonstration program, allowing up to 50 candidates, and 99,999 votes. He was therefore limited as to the number of candidates (10) who could receive the same preference number.
So, Meek’s method copes perfectly well with giving equal preferences to multiple candidates – the NZ STV calculator would almost certainly have no trouble whatsoever processing EQP votes (assuming that an excessive number of candidates were not permitted to have the same preference number, bearing in mind that several sets of candidates can have the same, different, EQP numbers).
Having called you out on this, I still say, in my computer programming ignorance, that allowing 35 or more candidates to have equal preference, not to mention several sets of several other candidates also having the same EQP numbers, whether using Meek or Schulze, would test any computer system, but, I may well be wrong; I would hope that I am.
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Legal Beagle: Voting in an STV election, in reply to Katharine Moody,
Yeah, I reckon I helped elect folks I didn’t want elected :-).
But by doing that, you made sure you didn't help elect those you *really* didn't want. So don't worry, you did good.
However any of us vote, it's all in the 'spirit' of STV. We can rank-order just one candidate, or 33 candidates, or any number in between. It's all good. Our STV system takes it all in its stride.
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Legal Beagle: Voting in an STV election, in reply to Katharine Moody,
Hence, I don’t like STV.
But, Katharine, it's just the same under multiple-FPP (whether or not in wards).
It's really hard for one person "to influence an STV vote [election]", especially if no-one else, or very few other people, vote the same way as you.
Being in Palmy (15 elected at-large), unless your vote ended up with the runner-up candidate, you probably did help to elect someone, or more than one, just not your most favoured candidate(s).
As for your husband, tell him it's easy. All he has to do is rank the candidates he likes in his personal order of preference. He can safely ignore the rest.
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Legal Beagle: Voting in an STV election, in reply to Steve Todd,
Ha!! If that had happened, Bowtell would have been eliminated (instead of the Liberal candidate) and the Greens would still have taken the seat (which they still hold, two elections later).
Okay, that's a mistake. Bowtell would simply have dropped down to second place; the Liberal candidate would still have been eliminated, and the Greens candidate would still have taken the seat. (That's what you get when you write in anger, and late at night (Thu).)
As a new candidate, she would have wanted to do as well as possible. I doubt very much she would have wanted to shed votes on the strength of a newspaper article.
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Legal Beagle: Voting in an STV election, in reply to Tim McKenzie,
You invite me to do a lot of work, and get back to you with the result of my endeavours. I don’t need to do that, Tim; I’ve got what I want (well, I wish all councils would take up the STV option). You’re the one who has some really hard work ahead of you, should you feel compelled to take up the challenge.
I just think that, at least in the single-winner case, we could do better.
Hmm, do you now? So, what are you doing about that, Tim?
(This is where you start to understand where I’m coming from. I’m going to be a bit hard on you, because you really have made me quite cross.)
From the sidelines, you in effect rubbish the good work that I and others did back in the 90s – Markus Schulze only developed his method in 1997, and I only became aware of it about 2001, the year the Local Electoral Act and Regulations were enacted / promulgated – but you give no indication as to what you’re doing to rectify the situation.
Are you going to analyse all the single-seat STV results since 2004, to identify all the possible Condorcet-criterion failures and monotonicity violations? You’re going to need to do that, you know, if you’re going to convince the relevant Internal Affairs officials that M-PV needs to be replaced with the Schulze method. Only they can convince the Minister of Local Government to take a proposal to Cabinet.
I spent the 90s analysing local election results from almost every local council, working out percentages of wasted / ineffective votes, demonstrating what a terrible system multiple-FPP is.
Have you prepared a paper yet, which clearly explains the Schulze method, in a way that ordinary people can understand? You’re going to need to do that, too, if you want to get officials on board. In 2000 (the big year for us), I really had my work cut out convincing officials that STV should be by Meek’s method.
Somewhere along the way, someone is also going to have to prepare a Schulze version of Part 2 of Schedule 1A of the Regulations, too. See: http://www.legislation.govt.nz/regulation/public/2001/0145/latest/DLM57125.html?search=ts_regulation%40deemedreg_Local+Electoral+Regulations+2001_resel_25_a&p=1 .
Given that you have admitted that “the computational complexity of its counting process puts me off[.]” you may have to submit a draft yourself. (Who knows, you might be the only person capable of doing that.)
I need to digress here. You then said “(Incidentally, the computational complexity of ordinary STV is another minor point against it, from my point of view, but it may well be better than Schulze STV on that score.)” From about the early 90s onwards, David Hill produced computer programs for, I think, 7 different STV counting rules, including the Royal Statistical Society (Meek’s method), Electoral Reform Society (1997 handcounting rules), Northern Ireland rules, Church of England (handcounting, with restraints) rules, and the New Zealand rules (Meek’s method). He told me that writing a Meek program was very straightforward compared to handcounting rules.
I believe this is confirmed by my 2004 Cargill Ward paper, which can be accessed at the link given at my first post here. Although it took me three weeks to produce, and nearly drove me mad doing it, it can be seen that the count is indeed straightforward; little more than simple arithmetic, in fact. (That, coming from me!!)
Okay, back to the purpose of this post. Have you had a chat with your local MP yet, to get his support? That would be worth doing. I first approached my MP in 1994. Eventually, it paid off big time.
Have you got other MPs lined up to fight your cause? We had, successively, David Caygill, Richard Northey and Rod Donald, in our corner.
Have you contacted SOLGM (Society of Local Government Managers) yet? I gave them a presentation in June 1999. A few months later, they recommended to the incoming Labour government that STV be provided for as an option for local elections.
Have you thought about whether or not the Schulze method should be used only for Mayoral elections, or for single-seat ward elections as well? In this regard, should councillors from single-seat wards really be elected by a completely different vote-counting method to those elected from multi-seat wards? That needs to be thought about.
Are you, and anyone else you can get to help you, prepared to spend the next five, ten years, campaigning to get what you want? I suspect not.
I’m going to assume you’ve done none of these things, and have no intention of doing so. That being the case, come 2019 and Graeme puts up another STV posting, and you think you might chime in at some point and say “I just think that, at least in the single-winner case, we could do better”, I hope you might care to think again.
(I will read your latest postings over the weekend.)
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Legal Beagle: Voting in an STV election, in reply to Tim McKenzie,
Wikipedia’s article on the monotonicity criterion has a section on real-life monotonicity violations that mentions two elections in Australia: one in which it was shown after the election that monotonicity was violated (in that if somewhere between 31 and 321 Liberal supporters had switched their votes to Labor, then the Liberal candidate would have won), and one in which it was identified before the election that monotonicity might be violated, and that Labor supporters might be better off if a few of them put the Liberal candidate first on their preference list instead.
Taking the second one first. As you say, the article said monotonicity *might* be violated, but actually, it wasn’t (and it wasn’t even close). This was the 2010 federal election in the Labor-held seat of Melbourne (it became marginal at the 2007 election). The new Labor candidate (Cath Bowtell) received 34,022 primary votes, the Greens candidate 32,308, and the Liberal candidate 18,760.
The article stated, “In what may be a first for Australian major party politics (or at least very rare), the only way Labor can guarantee itself victory in this seat is to boost the Liberal vote.” Later it said, “But a couple of thousand Labor voters voting Liberal with a second preference back to Bowtell (just in case it is not enough) should see off the Green menace.”
Ha!! If that had happened, Bowtell would have been eliminated (instead of the Liberal candidate) and the Greens would still have taken the seat (which they still hold, two elections later). As it turned out, nothing could stop the rise of the Greens in this seat.
So, in no way was this election a real-life example of a monotonicity violation, identified *before* the voting took place. And even if it was, does anyone seriously think many Labor supporters would really have voted Liberal, to improve the chances of the Labor candidate winning? If so, wouldn’t Liberal supporters vote for the Labor candidate to counteract Labor’s strategy? Of course not. It’s all nonsense. You only have to follow Antony Green’s ABC blog to see that, even after nearly 100 years, many Aussies just don’t understand STV / PV. Playing “silly buggers” with their vote would very much be a step too far.
To the first example. This is an example of a monotonicity violation being identified *after* the fact. (That immediately makes it meaningless, other than being an interesting academic exercise.) To ensure it did not happen, up to 321 Liberal Party supporters (of 7,576 who voted for the Liberal candidate) were required to vote for the Labor candidate, to keep Labor in second place, behind the Liberals, when the Nationals’ preferences were distributed. The Independent candidate (the eventual winner) would then have been excluded and his preferences would not have favoured Labor anywhere near sufficiently for the Labor candidate to get up.
Those 321 Liberal voters could not have known, when voting, that such a situation would occur. To say, after the outcome is known, that they – how would they have identified themselves? – should have voted for the candidate they *really* oppose (who would, in most cases, have been at-least their third-preferred candidate), is just a nonsense. They voted their true preferences and the votes fell where they did. You can read all about it here: https://en.wikipedia.org/wiki/Frome_state_by-election,_2009 .
And, lo and behold, the Independent candidate, Geoff Brock, was re-elected at the following two state elections, increasing his primary vote both times, and is now a cabinet minister in the Labor government. So there you go.
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Legal Beagle: Voting in an STV election, in reply to Tim McKenzie,
Despite saying I’d “leave it that”, I have given further thought to your responses on Wednesday 10 August, particularly regarding nonmonotonicity. This is the first of three posts.
(I have seen your latest postings – at 7.30 on Friday night). I’ve had a quick look, but, I’m sorry, I’m on a roll here, so they will have to wait. I’ve been working on these responses off and on for the last 48 hours.)
I have dug out a letter from the late Dr I D (David) Hill (he died in September 2015), which he wrote to me in August 1995. In it, he gives me his thoughts on nonmonotonicity. It was his first letter to me, after I had written to him, and he is aware that I am an STV (electoral systems) newbie. His comments may not do much for you, but they may be of interest to others (if we haven’t driven them away).
First, though, just a quick further comment about the Condorcet criterion, that you think so important. It is really only a single-seat matter, and I just want to emphasise again that I would not like to see later-no-harm dispensed with, to guarantee the election of a Condorcet candidate (if there is one), for the reasons previously given. In the multi-seat case, it is wrong to even want it always to happen, because, as I said upthread, it would be absurd not to elect ABCD in the example I gave.
On the question of nonmonotonicity, David said—
“I think that this has to be taken seriously in that, however rarely it may happen and however unobvious it may be when it does happen, it is in principle so nasty that it would be madness not to avoid it if it were possible to do so without introducing other faults that are at least as bad. Anyone who claims that it must be got rid of has to be asked which other of Woodall’s four features should be accepted instead — if they say “none of them” they simply do not know what they are talking about.
[To explain, D. R. Woodall (in Discrete Mathematics, 66, 209-211, 1987) puts forward four properties that we should like any electoral method to have. These are—
1. Increased support for a candidate who would otherwise have been elected, should not prevent that candidate’s election.
2. Later preferences should neither help nor hinder earlier preferences.
3. If no second preferences are expressed, and there is a candidate who has more first-preference votes than any other candidate, then that candidate should be elected.
4. If the number of ballots marked X first Y second, plus the number marked Y first X second, is more than half the total number of ballots, then at least one of X and Y should be elected.Furthermore, the method must work for any number of seats and any number of candidates. Woodall’s Theorem states that to find any system that meets all these requirements is impossible.
David then states that this is proved as follows. Suppose that there is such a system: then since it works for all cases, consider the case of 3 candidates for 1 seat, and the following 12 elections.
I won’t set out the 12 elections, but he cleverly shows that “This proves that the system must elect A from election 6, but it must elect B from election 12. But these are identical elections!! Therefore, the system cannot exist.]
“In applying Woodall to FPTP we have to consider voters’ wishes rather than what is written on ballot papers, for obviously second preferences cannot come into it if you are not even allowed to express them, but that does not mean that voters do not have any. It then obeys features 1, 2 and 3, but fails badly on number 4.
“Non-monotonicity can be serious in practice in the single-seat case. Suppose opinion polls show that, in a straight fight, candidate A could probably beat B but A would lose to C. Suppose also that A is likely to get the most first preferences though fewer than 50%. Then there will be a temptation for A to get some supporters to vote for B hoping that C instead of B will be excluded on the first count. It could happen and it could work but, for the sake of usually getting better results, we have to accept it.
“In the multi-seat case, any such manipulation is almost impossible. When I vote by STV I know that the trouble could occur, but that knowledge gives me absolutely no clue whatever of what I should do to make non-monotonicity work for me. Theoretically all systems are subject to manipulation, but in practice multi-seat STV is one of the safest.
“The trouble has to be compared with the advantages of STV in getting approximate proportionality by voters’ wishes, whatever they may be, not merely by political party. If the voters think party important, the party results will show it, but if they think any other feature more important, the results will show that. Only the STV principle, so far as I know, is capable of that and party-list systems do not even try to attain it.”
I know you understand all this, but I’m just laying the groundwork for my next post, on the Melbourne and Frome so-called monotonicity violations, that you drew to my attention.
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Legal Beagle: Voting in an STV election, in reply to Brent Jackson,
Thanks, Brent.
Again (groan), I forgot to separate out (from the 'M') the full-stop.
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Legal Beagle: Voting in an STV election, in reply to Tim McKenzie,
Please correct me if I’m wrong, but I think you’re thinking of a “vote” as something that a voter gives to a particular candidate, as in FPP.
Thank you, Tim, for spending so much time responding to my (I suppose) criticisms. I am about done now, having spent the last two nights on this - my fault, I know - but I will give you the courtesy of one more, more calmly expressed, response.
The extract, above, is correct. That is how I think of an STV / M-PV vote. I realise now you have been arguing from the point of view of voter theory, whereas I have been arguing from the point of view of ordinary people voting in public elections. I also now realise you were primarily talking about M-PV, whereas I was talking primarily about multi-seat STV.
I emphasise that I prefer later-no-harm because it gives ordinary voters the confidence to rank the candidates in their true order of preference. If they thought their later preferences might harm their earlier preferences, they wouldn't give them, and we'd be back to FPP again.
As I said (implied) to Graeme, general society would need to be far more sophisticated than it currently is, for more intricate versions of STV to be imposed on them. At the moment, you find that greater sophistication / education in private societies, which is why I imagine Shultz-STV is being used in an increasing number of them.
I have tried my best to follow Markus' work, but I just don't have the maths to keep up. I was in e-mail correspondence with him about 15 years ago. He photocopied an entire book and sent it out to me. A very nice chap.
I'm not too concerned about the monotonicity violation in Frome. Except for Tasmania and the ACT, the Aussies have completely ruined STV (although the recent rule-changes for Senate elections were an improvement). For lower house PV elections, voters have to rank-order every candidate. The parties also hand out how-to-vote cards which, I understand, most people follow. So, it would not have been too difficult for polling to reveal that a monotonicity violation was in the offing. Such violation could not be revealed in respect of, say, a Wellington mayoral election.
I have previously responded elsewhere (in 2010) to the possibility of using more advanced versions of STV. The one I prefer is called Sequential STV, co-written by David Hill. The authors admit that Sequential STV cannot be guaranteed to find a Condorcet winning set, even where one exists, but that that does not shake their belief that Sequential STV is a good system.
Although Sequential STV violates later-no-harm and later-no-help, I would happily use it in a private election. The results output on David’s STV program is so opaque, however, that there would very likely be public resistance to its continued use in public elections, because it cannot easily be seen how the result was arrived at.
This is what I said, and I’ll leave it at that.
It is a truism that, just as the candidate who is “first past the post” is not necessarily the correct winner, the candidate who is “last past the post” is not necessarily the correct candidate to exclude. This is an inevitable consequence of the guarantee in STV elections that later preferences cannot upset earlier preferences (…). It is this guarantee that gives voters the confidence to rank-order candidates in their own true order of preference and not have to worry about what other voters might be doing. (Under STV, there is nothing to be gained by voting tactically. Indeed, it could well backfire on voters in that the candidate(s) they really want could be excluded through lack of support.)At least three systems that I know of have been devised that keep candidates in the running, who would otherwise be excluded early, so that they might benefit from later preferences. They are all what you might call “experimental” and have not been used in real [and certainly not, public] elections.
The authors of one such system (called ‘Sequential STV’) have this to say, as to whether or not their system should be “recommended for practical use”—
“Should it be used?
“With this new version, should it be recommended for practical use? That depends upon whether the user is willing to abandon the principle that it should be impossible for a voter to upset earlier preferences by using later preferences. Many people regard that principle as very important, but reducing the frequency of premature exclusions is important too. We know that it is impossible to devise a perfect scheme, and it is all a question of which faults are the most important to avoid.
“In considering this, we need to take into account, among other things, that the true aim of an election should not be solely to match seats as well as possible to votes, but to match seats to the voters’ wishes. Since we do not know the wishes we must use the votes as a substitute, but that makes it essential that the votes should match the wishes as far as possible. That, in turn, makes it desirable that the voters should not be tempted to vote tactically.
“They would not be so tempted if they felt confident that later preferences were as likely to help earlier ones as to harm them, and if they could not predict the effect one way or the other. At present, we see no reason to doubt that these requirements are met.
“All things considered, we believe that Sequential STV is worthy of serious consideration.”
Should STV be modified to reduce “the frequency of premature exclusions”, the later preferences of some voters would help earlier preferences, the later preferences of other voters would harm earlier preferences, and the later preferences of other voters still, would both help earlier preferences for some candidates and harm earlier preferences for other candidates. Such consequences of modifying STV would *very* likely occur in an 11-seat electoral area (such as the Central Ward) where, this year, there are 39 candidates and some 30,000 voters.Simple electoral systems are prone to giving unfair outcomes. To achieve fair outcomes (based on the votes cast) you have to complicate them a little. But, to paraphrase one US academic in this field, there is a trade-off between “refinements” in STV (improved treatment of surpluses, as with NZ STV; improved process of exclusion) and the cost in manageability – for example, very complicated election rules, computer programming, and reporting of results (…).
We must keep in mind that we are dealing with public elections, not private elections. Therefore, bearing in mind that STV is still very new to New Zealanders, I think we should continue to allow the public to get used to what we have (over many more election cycles) before even thinking of making further refinements.