Tally ho

Attention Oscar voters:

You should have received your nominating ballot by now; if not, it'll be in your mailbox any day. You know how it works:

Look at the list of eligible films, rank your top five choices in all the categories nominated by whatever academy branch you belong to, select your five favorite films in the best picture slots, and send back the ballot.

But do you know what happens next?

Probably not. Most people don't. It can get a bit, well, to call it complicated might be an understatement.

The accountants at PricewaterhouseCoopers don't count votes the way you might expect, assigning point values and then tallying everything up. Instead, they use a strange, arcane, delightfully convoluted process called the preferential system.

The system can affect voters' strategies, alter campaign plans and turn dark horses into favorites.

You don't have to understand it before you vote — most voters certainly don't — but if you really want to cast an informed ballot, you ought have at least a grasp of preferential voting.

"It's like St. Anselm's proof of the existence of God," says the academy's executive director, Bruce Davis. "I can hold it in my head for a little while, but it slips away."

Normally, Davis adds, the only people who ever really want to hear the explanation are "groups of accountants or people like that. When I hear our members talking about it, I can tell they don't always understand."

But they should, of course, because it's important. Here, then, is a primer on the preferential system — how it works (more or less), and what its implications are (sort of) in the Oscar races.

1. They don't need no stinkin' computers. First of all, the system for counting Oscar votes is rarely used — anywhere. Some Australian elections have been using a variant for almost 90 years, two decades longer than the Oscars. Ireland uses it for certain elections, as has the San Francisco Board of Supervisors for the past year and a half.

In political races, the system instantly breaks ties and avoids the need for runoff elections — hence its alternative name, "instant runoff voting". At the Oscars, though, it works somewhat differently.

The process starts with a small number of PricewaterhouseCoopers employees, working at one of those celebrated "undisclosed locations" (definitely not the firm's downtown headquarters, they tell us), sorting ballots into stacks based on each member's first choice.

Yes, it's done by hand rather than by computer program. That's because it's safer that way — hackers can't attack paper notes kept in a safe in a locked room accessed by a handful of people. Plus, the defiantly low-tech system works best when stacks of paper are physically moved.