Understanding STV

October 2nd, 2010 at 12:00 pm by David Farrar

at Public Address has an excellent Q&A on STV. One or two blogs that purport to be specialist local body blogs have shown a dismal lack of knowledge on how works. They should also link to Graeme’s analysis. Some extracts:

But is it a good idea to rank everyone?

Yes.

But if I give someone I don’t like a rank, couldn’t this hurt the chances of candidates I like more?

No.

Your lower preferences cannot ever harm the election prospects of anyone you rank higher than them.

This is key. Don’t try and be strategic and working out who is most popular and hence I will rank them lower as they don’t need my vote etc. Just rank candidates in order of your true actual preference.

But what if I really don’t want to rank everyone?

You don’t have to. If there are a bunch of people whom you think are just as bad each other, or you know nothing about, your vote will still count. If the election comes down to race between people you haven’t ranked, you won’t help determine the result, but if you don’t mind which of them is elected, this shouldn’t bother you too much.

But if there’s someone I really really don’t want elected, I should rank everyone else above them

Yes.

This is again on the mark. If you have no opinions on a group of candidates you can leave them unranked. However if there is a candidate you definitely do not want to be elected, then you should rank all candidates and rank them bottom.

An informed vote is always a good idea.

Even for the District Health Board?

Okay, you got me. Health Board elections are stupid.

Yes they are. Please National get rid of them.

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11 Responses to “Understanding STV”

  1. excusesofpuppets (134 comments) says:

    Our mate John says that MMP is bad, therefore it must be.

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  2. Inky_the_Red (744 comments) says:

    >But is it a good idea to rank everyone?

    >Yes.

    Not sure that is correct. In the 2007 Northern Ireland Assembly elecltion both the DUP and Sinn Féin told there supporters to only rank their candidiates.

    Part of the issue with STV is to have the correct number of candidates. Too many can cost seats or get the wrong candidate electied for your group.

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  3. Chuck Bird (4,748 comments) says:

    “But if there’s someone I really really don’t want elected, I should rank everyone else above them”

    Yes.

    Good advise. I numbered them all and Colleen Brown was 24. I am sorry she has cancer but she is a serial trougher
    like her husband.

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  4. s.russell (1,580 comments) says:

    Part of the issue with STV is to have the correct number of candidates. Too many can cost seats or get the wrong candidate electied for your group.

    This is both true and false (which illustrates why STV is like politics meets quantum mechanics).
    If all voters vote on party lines first, and personal lines second, then it does not matter how many candidates a party runs. That’s because preferences will cascade WITHIN the party group.
    But such an idealised situation never occurs. There will always be people who rank (eg) Nat candidate A #1, Act candidate T #2, Nat candidate B #3, Monster Raving Looney candidate X #4 and Nat candidate F #5 etc.
    Such splitting may all cancel out, but running too many candidates can dilute your promotional effort.
    That said, such tactical considerations are prety marginal with STV. Best to just vote for who you want and let the maths take care of itself.

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  5. backster (2,120 comments) says:

    I agree with you about Hospital Boards there has to be a better way. They are just a magnet to opportunistic troughers and interest groups, expensive and in-efficient, and no-one knows anyone on them and why they are there.

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  6. pq (728 comments) says:

    Australia runs different electoral systems for :

    State elections
    Federal elections;
    Senate election

    I have never met an Australian who knows what is going on,
    much less one who can vote within these different systems.

    It is different here, we have no protection from the elected Parliament.
    Politicians [ like Rod Donald ] can invent and advertise interesting and favourable [to themselves ] systems.

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  7. IHStewart (388 comments) says:

    Totaly agree on DHB’s didn’t have a clue who any of them were so decided the least irrational thing to do was to vote for health professionals. In retrospect though it might have been better to have looked for anyone who was batshit crazy and voted for them on the grounds the government would be forced to sack them if elected and appoint a commissioner.

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  8. Interested Party (61 comments) says:

    I agree it’s a stupid system for health boards, so I just voted 1-18 in the order of the voting list – just as much chance getting the best candidates voted

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  9. Inky_the_Red (744 comments) says:

    s.russel your explanation is PR not STV.

    if 5 candidates are being elected in an electoral region then each party needs to consider how many to candidates to stand. Stand too many and you risk getting the ‘wrong’ candidate elected (at the expense of the one the party hierarchy) Stand too few and you might miss a seat.

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  10. Graeme Edgeler (3,274 comments) says:

    Not sure that is correct. In the 2007 Northern Ireland Assembly election both the DUP and Sinn Féin told there supporters to only rank their candidates.

    It is correct in New Zealand.

    I do not rule out that some difference in the system used in Northern Ireland means it wouldn’t be true there (although I very much imagine it would be) but in New Zealand there are no downsides to continuing with your ranking down to your “enemies” and ranking them from least to most offensive.

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  11. rouppe (940 comments) says:

    My strategy for voting on C&CDHB

    1) Identify all those that say they are existing board members and rank them last
    2) Identify all those that say the current board is a failure and is fucked, and rank them first
    3) Rank the rest in the middle

    C&CDHB is seriously failing. Compare it to the performance of Hutt DHB and there is daylight between them. So the current board must be seriously incompetent.

    My 2c worth anyway

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