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
