Nevertheless, I still think it’s helpful to have an understanding of the broader principles that form the basis of STV. This is especially true when you consider that the majority of criticisms of STV rely on fear-mongering, half-truths or outright lies in order to deceive people into voting against it; having a bit of knowledge will help you recognize the valid criticisms from the dishonest ones.
So the following is an explanation that works around the nitty-gritty math and calculations that can overwhelm those who are unfamiliar with STV. It’s very much a simplification; but one that, hopefully, will better help you understand the underlying principles. So that you don’t just know what is happening but why as well.
The system can basically be summarized into a handleful of steps:
- Voters rank the candidates on the ballot in the order of their preference (1,2,3,4 etc...) indicating "if my top choice gets eliminated or elected, my next choice is who I will vote for in the next round of voting"
- Count the votes.
- If none of the candidates has a majority share of the vote (eg. 50% + 1 for a single member riding), then eliminate the candidate with the fewest votes and transfer their votes to the next choice on the ballot. Repeat step two.
- If a candidate has a majority share of the vote and there are still seats to elect, then eliminate the elected candidate and transfer their votes to the next choice on the ballot. Repeat step two.
- Repeat the above until all seats have been filled.
Explanation of BC-STV in a single-winner election.
Explanation of BC-STV in a multiple-winners election.