How FiveThirtyEight’s March Madness Bracket Works

In contrast to the parity of the recent past, this year’s NCAA men’s basketball tournament has a clear frontrunner: the undefeated Kentucky Wildcats. FiveThirtyEight’s March Madness Predictions give the Wildcats a 41 percent chance to win it all and finish 40-0. Kentucky’s chances are well ahead of a group of teams — Villanova, Arizona and Wisconsin — that have about a 10 percent chance each.

I’ll have a longer take on the Wildcats and this year’s top-heavy bracket on Monday morning. But for now, we wanted to be sure you saw our numbers as soon as they were ready. You can find our interactive here, including the probability of each of the 68 teams invited to this year’s dance advancing to each round of the tournament.

The methodology behind our forecasts is largely the same as in past years. Our forecasts have done reasonably well — “calling” the winner of the tournament correctly in two out of the past three years. And they’ve been well-calibrated historically, meaning the teams we’ve listed as (for instance) 70 percent favorites have in fact won about 70 percent of the time. We don’t see a lot of reason to mess with our system.

At the core of the forecasts is a power rating for each team estimated from a composite of five computer-generated power rankings and two human rankings. By nature, our rankings are pretty conservative since they blend information from several different systems together.1 These are the five computer systems we use:

ESPN’s basketball percentage index (BPI). (Specifically, we use the variant of BPI called PVA, which translates team ratings into point spreads.)Ken Pomeroy’s pythagorean ratings.Jeff Sagarin’s “predictor” ratings.Joel Sokol’s LRMC ratings.Sonny Moore’s power ratings.

The two human rankings are:

The selection committee’s

While all of the Tar Heels’ ratings are pretty close, their worst one is from where the committee placed them on the S-Curve, 13th, suggesting that they were slightly underseeded. Their best rating comes from their preseason ranking, by contrast. We know it might seem unusual to blend preseason rankings with six other systems that rank a team’s current form, but there’s a