They Shoot Oscar Prognosticators, Don't They?
A Primer on Preferential Voting
By J Don Birnam
February 19, 2014
The system used to select Best Picture since the Academy expanded the field of nominees is known as “preferential” or “instant runoff” voting, famously the method used for Australian parliamentary elections. So, how exactly does the system work? Bear with me and it hopefully will become clear in a few moments.
Instead of selecting one pick for Best Picture in any given year, Academy voters are now asked to rank the Best Picture nominees from their favorite (“1”) to least favorite (“9”). Under the rules, a movie needs half plus one #1 votes to win Best Picture. For purposes of this exercise, assume there are 1,000 voters and that each ranks all nine contenders. In that scenario a movie needs 501 first place votes to win. The PricewaterhouseCoopers accountants in charge of tabulating Oscar voting results start their task by making nine piles, one for each of the Best Picture nominees, and in each pile placing the respective ballots that voted for that particular film as their #1 choice. What happens if no movie gets the needed 501 #1 votes? It is a safe bet that in most years, simply given the large number of nominees, no movie is going to get as many as half the votes outright. That is where redistribution kicks in - the part where it gets confusing for some people.
Redistribution works as follows. If no movie has crossed the half plus one threshold, the accountants go to the pile of the movie with the fewest number #1 votes and look at what each voter put as their #2. Suppose, for example, that of our 1,000 voters, only 30 of them picked Nebraska as their favorite of the year, the fewest of any of the nine nominees. The accountants will then take those 30 ballots and redistribute them to the piles of the movies selected as #2 in each of those 30 ballots. Effectively, the ballots are split up into one of the remaining eight piles as if they had originally selected a movie other than Nebraska as their #1 pick. That was probably the hardest part to understand, so if you are still with me you are in good shape.
At that point, there are eight remaining contenders, and each (in theory) has seen their respective vote totals increase by however many votes they got allocated from the movie that was first eliminated - again, the movie with the fewest number one votes. If any movie has crossed the threshold needed to win, the process is over and we have a winner. So, in our example, if 499 people selected Gravity as their #1 movie, but two people who selected Nebraska as their #1 selected Gravity as #2, Gravity will win when those two Nebraska ballots are redistributed to it in the first round of redistribution.
If this does not happen, the process of eliminating movies and redistributing ballots continues until one movie hits or crosses the 501 mark. So, to be abundantly clear, the next step is to go to the pile of the movie with the fewest votes after the first redistribution occurred and redistribute that movie’s ballots. Note that after the initial count a movie may have been in, say, eight place, but the redistribution of the ninth place movie’s ballots could theoretically bump that movie up enough so that it becomes the seventh or higher place movie, allowing it to survive at least another round.