(Disclaimer: Several drinks consumed.)
Alright. I'm sick of explaining to people how preferential voting works when they turn around and say "Hurr I'm not voting for anyone but the major parties / going to write 'fuck you' on my ballot paper because there's no point and I'm just wasting my vote".
Listen up kids.
Let's say there's five parties, conveniently labelled A through E. Your ballot paper would look something like this:
Party A [ ]
Party B [ ]
Party C [ ]
Party D [ ]
Party E [ ]
Now let's say you vote like this:
Party A [3]
Party B [2]
Party C [1]
Party D [5]
Party E [4]
Come election night, all the votes are tabulated. To start with, they go through and separate everyone's votes by whoever they put the #1 next to. Let's say you live in an electorate of 5,000 people.
Here's the running tally at the first count:
Party A - 1,500
Party B - 750
Party C - 250
Party D - 1,500
Party E - 1,000
OH NOES! You cry. Party C didn't win! My vote is wasted!
WRONG. In order to win a seat in a preferential election, a party must have 50% of the vote, plus 1 - in this case 2,501 votes. So what happens now?
All of the people who voted for party C as their number 1 get redistributed as their number 2 choice. You voted for party B as your second choice, so your vote goes there. 250 votes for Party C get assigned by their #2 selection to the other parties.
Party A - 1,575
Party B - 775
Party C
Party D - 1,600
Party E - 1,050
As no one has 50% + 1 of the vote, party B is out of the race. All of party B's votes (which now include yours) are redistributed according to the next preference on the ballot sheet. (Yours goes to Party A as you put them down as #3)
Party A - 2,075
Party B
Party C
Party D - 1,700
Party E - 1,225
Not quite there yet. Party E is struck off, and their votes redistributed. Yours goes nowhere as Party A is still in the running and you indicated that you'd prefer them over D & E.
Party A - 3,075
Party B
Party C
Party D - 1,925
Party E
Party A wins. Holy shit, your vote wasn't wasted - while your first choice didn't get in, the fact that you knew what you were doing means that your third choice got in.
If this isn't clear,
go read this. Because if you EVER tell me that voting for a third party in Australia is stupid because you're just "wasting your vote", I will punch you in the crotch. Repeatedly.