Talk:Single transferable vote

Older discussion at Talk:Single Transferable Vote/Archive1

Images

We'd do really well with some good pictures of actual STV ballots to show what voting is like. An Australian ballot demonstrating group voting tickets, for instance, would round out a section nicely. Also, replacing that MS Paint picture that's in there currently would be nice :) (unsigned 21:18, 28 May 2005 User:Scott Ritchie)

I am not sure about ballot papers: these really belong in the preference voting page; even group tickets are a form of preference voting. --Henrygb 22:13, 31 May 2005 (UTC)

Why not have them here as well? Nothing prohibits us from using the same image in multiple articles (the one there is used that way already), and they certainly add information about what STV is like, and since afterall this is meant to be an encylopedic article on STV, that can only help make it better. Scott Ritchie 00:02, 1 Jun 2005 (UTC)

The article is fairly long as it is. And there is plenty more on preferential voting (e.g. the potential for confirming vote buying) which could also go here. But I don't really care. --Henrygb 19:55, 2 Jun 2005 (UTC)

I added one for the Aussie system. It's not a real ballot I don't think but it gets the idea across. Felix the Cassowary 03:56, 12 July 2005 (UTC)

First preference and party preference

The proportionality section is getting a little apologetic again, saying that it is impossible to determine whether first preferences reflect party preferences, and saying this twice. It is in fact easier to measure for STV than for any one candidate per party system or SNTV since the proportion of people who transfer from a candidate of one party to a candidate of a different party when they could have gone to a candidate of the same party can be measured. It might be sensible to look at early transfers to avoid donkey vote effects. In Malta a quick clance suggests this seems to be about 1%, in Northern Ireland perhaps about 15-20%, at least for distinctive parties - the smaller non-sectarian parties seem to swap votes more. --Henrygb 22:10, 8 Jun 2005 (UTC)

• A measure of party loyalty, however, is still not a measure of party preferences. For instance, it could be the case that the first five candidates on my ballot represent moderates from another party. More importantly, you need a mechanism for distinguishing between early defectors (say, one who ranks only one or two candidates for a party before choosing another) and late defectors (say, one who ranks all but one candidate from the same party before picking candidates from another) - do you count them both equally as members of the same party, or both equally as defectors? Scott Ritchie 23:08, 8 Jun 2005 (UTC)

NP hard

I think the NP hard statements are a little over the top. Yes, I accept that it is possible to construct a situation where it is difficult to compute and that is what the proof does. But what is suggested here is that STV tactical voting is always NP-hard. That is the equivalent of saying that finding a prime factor of a large number is hard: yes it is for some, but not for 1000000000000000000000000000000000000000000000000000 or indeed any even number. Take for example the Knockiveagh 21 May 1997 election [1] (about 2/3 of the way down the page that is linked from a related page). It seems obvious to me that if the SDLP first preferences had been evenly split 805/804 rather than 946/661 then the party would have won two seats rather than one. Many parties try to manage their votes in this way especially in systems where full preferences are not expressed, and many voters are happy to follow guidance (as they are in SNTV where balancing the votes is even more important). --Henrygb 17:46, 10 July 2005 (UTC)

• Tactical voting is always NP-hard, however NP-hard problems are not always unsolvable. This is particularly true in the small districts of only 4 or 5 representatives common to many of the STV systems. Also, it is quite possible that erroneous assumptions about the viability of their strategy are being used by election campaigns. Also, tactical voting is easier in systems not using Meek's method, as stated in the article. Was Knockiveagh using that method in 97? Scott Ritchie 22:53, 10 July 2005 (UTC)

Trying to balance first preference votes between candidates from the same party is a standard vote management technique in many systems where there are substantial numbers of incomplete preferences. Getting it to work is sometimes difficult because some voters will not take instruction, but the mathematics of it are relatively simple:
If at the final stage there are three remaining candidates all under quota, two of which are from your party and one from another, and your two candidates have more than twice as votes between them as the other candidate, then if your candidates' support is evenly shared you will win both seats. If not then you may not. There is more likely to be balanced support in the final round if there is balanced support in the first round.
To stop that you would need a system which reduces the quota as votes drop off - does Meek's method do that? As far as I am aware, Meek's method is used in New Zealand and not in the other countries listed. If so, the article should make that clear. It is certainly not used in Northern Ireland, the Republic of Ireland or Malta. I don't know about Australia. --Henrygb 00:29, 11 July 2005 (UTC)

Meek's method does reduce quota as votes are exhausted.--TreyHarris 00:44, 11 July 2005 (UTC)

Indeed. I found this [2] --Henrygb 01:21, 11 July 2005 (UTC)

Article could really use some expansion on the Irish bits

This article could benefit a great deal from some review of the history of STV in the Republic of Ireland and Northern Ireland. The articles on Ireland, Gerrymandering, and The Troubles hint that STV might have come about as a solution to some of the serious problems caused by the old voting system that may have lead to the Irish civil rights movement, such as disenfranchisement via gerrymandering. I don't know anything about the history myself, however, but Wikipedia could certainly use some review of this topic (either here or in the related Irish articles). I'm going to tag this article for expansion. Scott Ritchie 06:53, 11 July 2005 (UTC)

The only slight problem with this is that STV there started with the Irish elections, 1921. It continued in the Free State/Eire/Republic despite the desire of leading politicians to end it. It was stopped in Northern Ireland (late 1920s?) because too many Labour or other non-sectarian representatives were being elected. Then came local gerrymandering (most notably in Derry/Londonderry). In Northern Ireland it came back into local government in 1973 where it has remained. It is a matter of opinion whether electoral areas are still carefully drawn: see for example Belfast [3] and compare unionist/loyalist Court with nationalist/republican Lower Falls next door. Meanwhile in the Republic the average number of winners in a constituency is below 4. --Henrygb 19:51, 11 July 2005 (UTC)

And even Derry/Londonderry carries a curious result in 1973: the United Loyalists and the Alliance Party between them won a majority of the first preferences, but the SDLP, Nationalists, and Republican Clubs won a majority of the seats under STV.[4] --Henrygb 00:17, 12 July 2005 (UTC)

How's that curious? Why would STV have preferences if that sort of thing was forbidden, or to be considered odd? It happens all the time, because STV isn't proportional on first preferences, but proportional on the balance of preferences. (A controversial case of it happened in the last Australian Senate election for Victoria, but that was due to an oddity of the Australian system allowing Parties to allocate preferences if the voter lets them—and it probably won't happen again.) Felix the Cassowary 02:13, 12 July 2005 (UTC)

Wasted votes

I am not convinced that we can say something like "the number of wasted votes must by necessity be less than a quota". Two examples, the first plausible, the second not:

• A one seat STV election where 60% of the first preferences go to one candidate: the quota is marginally over 50% of the votes, but the wasted votes are the 40% going to the other candidates plus the 20% of the total votes which the winner won but did not need to win on the first round, making virtually 60%.
• A ten seat STV election with eleven candidates: 1000 voters give a full preference listing for the first 10 candidates in various orders with the candidate Z in last place every time, while 1 voter puts the candidate Z first. The quota will be 1001/11+1=92, but the number of wasted votes will be 980 (those of the 1000 which would not have made any difference to the result if they had not been cast) plus 1 for the first preference for candidate Z.

Clearly you could define wasted votes so as to ignore unnecessary votes for winning candidates, but taking that as your definition would justify an STV system which did not transfer surpluses, leading to fewer wasted votes. --Henrygb 22:45, 28 July 2005 (UTC)

• • Hmm, I see what you're saying. I will note that in your second example, the candidates are winning not because they fulill quotas, but because all other candidates were eliminated. It is still true, however, that the number of remaining excess votes (a subset of wasted votes) will always be less than one quota. Scott Ritchie 23:29, 28 July 2005 (UTC)
    • I had imagined that in the second case, the surpluses would shuffle round the first 10 candidates until they each had 92 or more; if there had only been 20 votes for them together and 1 for Candidate Z then the surpluses would shuffle round until the first 10 each had 2 votes (or the quota if a smaller fraction). But it doesn't really matter. --Henrygb 19:55, 29 July 2005 (UTC)

The New Example

I don't want to knock other people's hard work - but I don't find thenew example that easy to follow - IMNSHO the pictures are distracting and the star votes aren't that clear. I do think a simple numerical table suffices. Maybve I'm just being a miserable old git. Sorry. --Red Deathy 12:31, July 29, 2005 (UTC)

• I cleared out some of the unnecessary pictures, so it should look a little smoother now. Also, the stars were just an arbitrary character I picked - perhaps something larger and easier to color-differentiate would be better. I do think the added visibility of seeing which votes are transfering is helpful, however - I did this demonstration live with toothpicks, and found that people grasped it a lot better when there was a visible movement of certain toothpicks from one pile to another. The colored stars are an attempt to illustrate that sort of movement - something we can't get with numbers. Scott Ritchie 10:50, 30 July 2005 (UTC)
• My only complaint is that the stars in the example are too hard to distinguish. All of the reddish-orange colors look about the same. Even if they don't match the pictures, some of them should be changed to different colors like green, purple, or black. I also suggest a more visible vote marker, like ♦, except I'm not sure if entities like that show up in everybody's browser. Maybe even just a bold x. RSpeer 06:59, August 15, 2005 (UTC)
  • You're definately right about this. I went and changed the stars to x's and made the colors more visible. My concern, however, is with people who are color-blind in various ways - perhaps we can find one to comment on the current colors, altering them with dashes of red and blue if need be. Scott Ritchie 21:37, 16 August 2005 (UTC)

US dates

Lo all - I've shoved the list of US cities that used STV off to a specific list page, though useful; I don't think it belonged in the article.

If anyone could scare up some dates to put on that page I'd be chuffed to bits.--Red Deathy 07:48, 28 September 2005 (UTC)

Malta Encore

Nevertheless, failures to produce partisan proportionality exactly analogous to the party affiliations of top choice candidates as occurs in list PR elections can be controversial. For example, in Malta in 1981 the party winning more than half the top preferences won less than half the seats, resulting in a constitutional crisis: see below.

My problem here is linking the first sentence to the second - in essence the Malta situation was STV behaving like a party list system, with simple droop quotas - if you'd used D'Hondt or any of the others with the same constituency boundaries you'd have got much the same result. OK, list constituencies use bigger electorates (because counting is much simpler) but the fact is that it isn't an explicitly STV problem, and I think that needs to be got across. --Red Deathy 12:43, 29 September 2005 (UTC)

You cannot have it both ways. Either it is impossible to judge how proportional STV is (then don't call it PR) or there are examples of controversy. If Malta had for example open list PR, then the natural response would be larger constituencies or even a national constituency. But STV makes larger constituencies harder as described at the end of the section Single_Transferable_Vote#District_size. Having 100-200 candidates from a single party would be hard even in Malta. --Henrygb 17:05, 29 September 2005 (UTC)