Are Seven-game Baseball Playoffs Fairer than Five-game Series When Home-field Advantage Is Considered?

Conventional wisdom in baseball circles holds that a seven-game playoff series is fairer than a five-game series. In an earlier paper, E. Lee May, Jr. showed that, treating each game as an independent event, a seven-game series is not significantly fairer. In this paper, we take a different approach, taking homefield advantage into account. That is, we consider a given series to consist of two disjoint sets of independent events—the home games and the road games. We will take the probability of winning a given road game to be different from the probability of winning a given home game. Our analysis again shows that a seven-game series is not significantly fairer.