[EM] Explaining PR-STV

[Jan Kok]

This is a very nice, clear explanation or PR-STV. I would suggest
mentioning that the quota is commonly set at greater than 1/(N+1)
times number of valid votes. Thus, with 5 seats and 600 votes, a
candidate who gets more than 100 votes is guaranteed a seat.

I'm not convinced that PR can lead to "instability." Isn't that more a
property of the parliamentary system? After all, in the US we can have
congress be at 50/50 Dems/Republicans, where just one defection can
swing control to the other side, yet our government doesn't seem all
that "unstable".

Cheers,
- Jan

On Fri, Aug 28, 2009 at 7:08 AM, Raph Frank<raphfrk at gmail.com> wrote:
> One of the hardest parts about PR-STV is actually explaining it.
>
> Anyway, this was an approach I was thinking of.
>
> I think it hits the main points by covering the reasons rather than
> the detailed maths.  Most people in PR-STV countries understand the
> method, as they experience it from a voter's perspective, rather than
> a counter's perspective.
>
>
> PR-STV is based on 4 main principles
>
> 1) Each voter gets 1 vote and they can vote for any candidate they want.
>
> ** All votes are equal. **
>
> 2) The 5 candidates who get the most votes get a seat.
>
> I am assuming 5 seats are to be filled, but the system works for any number.
>
> 3) If you vote for a losing candidate, your vote is transferred to
> your next choice
>
> This reason for this rule is is so that you can safely give your first
> choice to your favourite even if he is a weak candidate.
>
> If he doesn't win, your vote will be transferred to your next highest
> choice, until it gets to a candidate who can win a seat.
>
> ** Voting for a weak candidate doesn't mean you are "throwing your
> vote away". **
>
> 4) If you vote for a candidate who gets more votes than he needs, the
> surplus is transferred to your next choice.
>
> The Quota is simply the minimum number of votes a candidate needs in
> order to be guaranteed to be one of the top 5.
>
> If 5 candidates had a quota of votes, then even if all the rest of the
> votes go to one of the other candidate, he would have less than the
> quota.
>
> If you vote for a candidate and he gets twice the Quota, then he only
> needs half of your vote to get elected.
>
> He keeps half of your vote and the rest of your vote would go to your
> next choice.
>
> ** Voting for a strong candidate also doesn't mean you are "throwing
> your vote away". **
>
> The Ballot
>
> The ballot allows the voter the rank the candidates (who is your
> favourite candidate, who is your next favourite and so on).
>
> ** This gives the voter full control over how their vote is transferred. **
>
> The Count
>
> In the first round, all the first choices are counted.
>
> If no candidate is greater than the quota, then the weakest candidate
> is eliminated and his votes are transferred.
>
> Otherwise, the candidate with more than the quota is declared elected
> and his surplus votes are transferred.
>
> This is repeated round by round until all 5 seats are filled.
>
> --
>
> There would need to be a discussion on the loss (or lack thereof) of
> the "local-link" due to the larger constituencies and unstable
> governments.  Also, there would need to be a discussion of
> proportionality.  For example, show some first past the post results
> and some PR-STV country results.
>
> Also, there could be a discussion of the effective threshold due to a
> small number of seats.
>
> If there was an example of the count, it might also be worth giving
> the viewer an example ballot that is his ballot.  You could then say
> stuff like "unfortunately, your first choice (A) didn't get elected,
> so your vote goes to your next choice (B)".
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>