The only large voting bodies who do this are the PGA and the Oscars. That’s why there is a good chance what wins the PGA will win the Oscar. The PGA are 4,500 and the Oscar voters are around 6,000. I’m including after the jump an interview I did with The Wrap’s Steve Pond in 2009 about balloting. He was spot on.

Deep breath. Focus. Here we go.

1. How many votes would Avatar [or The Hurt Locker, or any other nominee] need to win the first round?If every single eligible voter casts a ballot, 2,889. (50% of the total number of votes cast is 2,888 1/2, so you go to the next largest number.)

2. Can you explain again the whole magic number thing and why certain films will be divided into piles?To start with, all the ballots go into piles. One pile for each of the 10 nominees. If somebody has 2,889 first-place votes, nobody can catch them so you have a winner. End of story.

If not, you determine which film has the fewest #1 votes — in other words, which pile of ballots is the smallest. That film is now eliminated from contention. You take each of its ballots, cross out the #1 film, and place the ballot into the stack of whichever film is ranked #2.

Then you recount the nine remaining stacks. If one of them now has 2,889, it’s over. If not, you take the smallest of the nine stacks, eliminate that film, and look to the #2 film on those ballots.

You keep doing this, round after round, until one film has more than half the votes. With 10 nominees, I suspect it will take several rounds to find a winner.

As you go along, in some cases you’ll eliminate a film, look at the #2 choice on its ballot, and find another film that’s already been eliminated. So then you keep going down the ballot until you find the highest-ranked film that’s still in the running.

One of the commenters on your board actually had the best analogy I’ve ever seen for how it works. In essence, you’re asking the voters, “Out of these 10 films, which one is your favorite?” You take their answers, eliminate the least popular film, and then ask, “Out of these 9 films, which is your favorite?” Then, “Out of these 8 films, which is your favorite?” “Out of these 7 films, which is your favorite?” Etc., maybe even all the way down to “Out of these 2 films, which is your favorite?” The preferential ballot allows you to answer that question over and over, until you get the same answer from more than half the voters.

3. If Avatar loses the first round, is the traditional wisdom that it can’t win because it isn’t a number 2 or 3 movie but a number one or a number 10?That is indeed the conventional wisdom, and I suspect it’s correct. Based on my playing around with critics’ Top 10 lists as if they were Oscar ballots, I suspect that in a field of 10 nominees, the eventual winner will be lucky to get 50% of those 2,889 votes in the first round. Which means you have to have those #2 rankings to stay in the game. I think it’s correct to assume that Avatar is more polarizing than Locker, and I’d bet that Basterds somewhere in between. So for Avatar to survive its lack of #2 and #3 votes, it’s going to need to come out of that first round with a big lead in the #1 votes.

4. Do you expect any real surprises for Best Picture to turn up as a result of the preferential ballot?No. Granted, the possibility exists for one of the two Up movies, say, to ride to victory on a wave of #2 and #3 votes. But I think there’s a limit to how much ground you can make up if you’re not in first or second place after the first round of counting. When I’ve run mock counts with Top 10 lists, the films that start out in the lead almost always stay there. I think Avatar and Hurt Locker will get the most #1 votes, and I think one of them is going to have enough #2s and #3s to prevail.