We live in a democracy. Majority rules, right? Not always. Not at the Oscars, anyway (necessarily). You’d think that the process of deciding the year’s Best Picture would be as clear-cut as to award the movie with the most votes. But it’s not, and hasn’t been since 2008. (It doesn’t necessarily work that way to determine the US President, so why should determining the year’s top movie be any different?)

In 2009, when the Academy of Motion Picture Arts and Sciences (AMPAS) expanded its Best Picture nominations from five to 10 (now the number of nominees can be anywhere between 5 and 10), it reintroduced its preferential voting system, one that was last used from 1934 – 1945. The system is pretty complex, and with over 7,000 ballots to sort, it takes about a week for those famed accountants at PricewaterhouseCoopers to determine the winners.

Understanding how the preferential ballot works can help to explain each year’s Best Picture winner—especially if the winner leaves you with a furrowed brow (“I mean, that movie was good, but it wasn’t ‘Best Picture good'”). So here’s how it works, in a nutshell:

Step 1: All voting members are asked to rank order all Best Picture-nominated films from best to least best.

Step 2: The accountants then create separate stacks (figuratively speaking), one for each nominated film.

Step 3: The ballots are reviewed individually and placed in the various stacks based on first-place votes. So, for example, if a ballot lists Dunkirk in the #1 spot, that ballot will be placed in the Dunkirk stack.

Step 4: This process continues until all ballots have been reviewed and stacked.

Step 5: The film with the fewest number of ballots in its stack is eliminated from contention, and those ballots are re-sorted into other stacks based on the second-place votes.

Step 6: The film with the fewest number of ballots in its stack is eliminated from contention, and those ballots are re-sorted into other stacks based on the third-place votes.

Step 7: This process repeats (over and over and over), going down the line until one film emerges with at least 50% plus one of the votes. That’s your winner.

(It’s worth noting that the preferential ballot is only used for the Best Picture category.)

So what does this all mean? Why did La La Land lose to Moonlight? Why did The Revenant lose to Spotlight?

This preferential voting system hurts polarizing films. It’s feasible that one film will receive the most first-place votes, but the same film could also receive a significant number of last-place votes. As films are eliminated through the sorting process, a polarizing film is highly likely to be removed from contention, thus clearing the way for a film that was most voters’ second, third, fourth, or even fifth choice.

The idea is that the winning picture will be the most universally liked—not necessarily loved.

And it’s for this reason that the category has proven more unpredictable over the last several years. For example, it used to be that Best Director and Best Picture went to the same film (with few exceptions). But that only happened once in the last five years (the most recent being Birdman in 2014).

How does this affect this year’s race? We’ll find out on March 4, but it’s my belief that films like Lady Bird or Get Out—both of which have received universal acclaim since their releases—stand the best shot at taking center stage at the 90th Academy Awards. Let’s just hope one isn’t erroneously called over the other.