11 October 2012

ACT elections: understanding Hare-Clark

| housebound
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The ACT Elections factsheet on Hare-Clark describes our vote-counting system. It claims to be a single transferable vote method.

The counting is based on a quota, which is the number of votes a candidate needs to get elected. (The factsheet describes how a quota is calculated.)

If you vote ‘1’ for a popular candidate who gets more than a quota, your vote is counted twice – once when you help the candidate get a quota, and again when excess votes are distributed at a reduced value. You also support someone you didn’t vote for because your vote helped create more than a quota that is then redistributed to everyone’s 2nd and later preferences – even if you only put a ‘1’ on your ballot paper.

What if you vote ‘1’ for someone who doesn’t get a quota? Your vote is distributed according to your preferences at their full value. Eventually it will end up with someone who gets a quota. If you didn’t number all the boxes, you might run out of preferences before you can elect a candidate: your vote is exhausted.

If a candidate gets a quota after getting reduced-value preferences from another candidates, any ‘1’ votes for them before then are safe. They stay with the no. 1 candidate and are no longer counted (other than to establish the quota). They still enable support for other people’s preferences, even though only the new votes from other excluded candidates are redistributed.

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housebound said :

Gallagher got about 1.5 quotas in first preferences in 2008. She got elected. Then the system then distributed all 1.5-quota of votes at a reduced value to the second preferenced candidates on people’s ballot sheets.

So if I voted Katy (1) then Carolyn (2), my first preference got Katy her quota (and helped get her elected), and my second preference would have got Carolyn elected. Not only that, because my first preference helped get Katy her quota, it also helped other people’s second preferences elect their candidates. I would have even indirectly supported Zed or Simon or Gulia or Barr.

In this situation, Katy only needed two-thirds of each first preference vote she got. So two-thirds of your vote was used to help elect Katy, and the remaining one-third of your vote was passed on to Carolyn.

Now, it’s true that in this situation you could have instead voted 1 for Carolyn, and then Carolyn would have recieved all of your vote. Carolyn would have been slightly better off, Katy would still have been elected, and all those other Katy votes would have been passed on at an infintesimally smaller transfer value.

This is called tactical voting – by not voting strictly in accordance with your real preferences, you’re able to advantage your preferred overall outcome. There’s a risk, though – obviously if too many Katy voters did the same thing, she might end up short of a quota.

It’s generally considered impossible to build a voting system based on ranked candidates which doesn’t provide an opportunity for tactical voting.

colourful sydney racing identity said :

‘If you vote ’1’ for a popular candidate who gets more than a quota, your vote is counted twice ‘ incorrect.

I didn’t really understand it either until I looked at this sample scrutiny sheet. From that, it looks like it works like this:

Gallagher got about 1.5 quotas in first preferences in 2008. She got elected. Then the system then distributed all 1.5-quota of votes at a reduced value to the second preferenced candidates on people’s ballot sheets.

So if I voted Katy (1) then Carolyn (2), my first preference got Katy her quota (and helped get her elected), and my second preference would have got Carolyn elected. Not only that, because my first preference helped get Katy her quota, it also helped other people’s second preferences elect their candidates. I would have even indirectly supported Zed or Simon or Gulia or Barr.

Yorick_Hunt said :

Jerry Atric said :

Mr/Ms Hare Clarke’s (or is it Ms/Mr with Robson Rotation) is the fairest known voting system for multiple candidates in multiple electorates. Unfortunately it falls down because the majority of voters haven’t a clue what they are doing past their first preference (including me!).

Personally I prefer a modified Ancient Greek system where you could scratch the names of people you didn’t like on a bit of pottery and have that person counted to be excluded. Thus you would end up with the government you least disliked.

You get my vote. … 🙂

This is completely off topic, but I was wondering (please help me here mods) if you’re related to Pork?

We need a “None of the above” option on each ballot paper.

Jerry Atric said :

Mr/Ms Hare Clarke’s (or is it Ms/Mr with Robson Rotation) is the fairest known voting system for multiple candidates in multiple electorates. Unfortunately it falls down because the majority of voters haven’t a clue what they are doing past their first preference (including me!).

Personally I prefer a modified Ancient Greek system where you could scratch the names of people you didn’t like on a bit of pottery and have that person counted to be excluded. Thus you would end up with the government you least disliked.

You get my vote. … 🙂

Mr/Ms Hare Clarke’s (or is it Ms/Mr with Robson Rotation) is the fairest known voting system for multiple candidates in multiple electorates. Unfortunately it falls down because the majority of voters haven’t a clue what they are doing past their first preference (including me!).

Personally I prefer a modified Ancient Greek system where you could scratch the names of people you didn’t like on a bit of pottery and have that person counted to be excluded. Thus you would end up with the government you least disliked.

This…

housebound said :

It claims to be a single transferable vote method.

….would seem to contradict… .

housebound said :

If you vote ’1? for a popular candidate who gets more than a quota, your vote is counted twice.

…this.

And doesn’t seem right to me, but trying to read that factsheet made me more confused.

colourful sydney racing identity4:34 pm 11 Oct 12

‘If you vote ’1? for a popular candidate who gets more than a quota, your vote is counted twice ‘

incorrect.

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