Expert: Referee Calls Consistent with Series Being Extended

Kevin Hassett is the director of economic-policy studies at the American Enterprise Institute, and an adviser to John McCain's presidential campaign. Like a lot of economist-types, Hassett has been inspired lately to poke around the available facts and figures to see if there is any evidence that the NBA, and/or its referees, may have influenced the outcome playoff games as former referee Tim Donaghy has alleged.

Hassett found no smoking gun.

But he did find some weird stuff in elimination games, when calls seemed to favor extending the series more than in other games.

He also found that home court advantage was much more important in the playoffs than in the regular season, which is a bit odd.

Both findings are consistent with what you'd find if you wanted to have as many money-making playoff games as possible. Basically, if every series ended in a sweep, there'd by very little opportunity to make money. However, if every series gets to Game 7 -- which happens when home teams win every game -- the teams and the League have not only three more chances to make money, but the three most exciting games of the series.

(Sidenote: Those money-making opportunities are essentially free. Other than bonuses that grow the deeper a team makes it into the playoffs, players play the post-season for free.)

Hassett explains several factors that could come into play if a team is being favored by the referees. For instance, they may shoot more free throws. They may also, he speculates, be able to play more aggressive defense, which would presumably lead to a lower shooting percentage by their opponents.

Hassett explains some of his findings on Bloomberg.com.

Later in the series, a home victory might be necessary for the games to be extended. In that case, the officiating bias might be greater. Sometimes a series might end before seven games if the home team wins. In those cases, the favoritism may be less. In the seventh game, the bias might disappear, as it no longer would serve any purpose. The series will end no matter what.

First let's look at Game 5. In the 2007 and 2008 playoffs, 25 series extended to at least five games. At times when the home team was leading three games to one, and another win meant the end of the series, the visiting team shot 1.1 percentage points better than the home team. When a home-team win doesn't end the series, the home team's field-goal percentage is 5.4 points higher on average than the away team's.

Let's turn to Game 6: In the 2007 and 2008 playoffs, in games where the home team was behind in the series, it was called for 4.1 fewer fouls on average than the away team.

In the seventh game the foul differential drops to just one during the past two years. That's little more than the regular season average.

All the data suggest there have been movements in the number of calls that are consistent with the suspicion that the NBA sought to extend series.

To be sure, such statistics prove nothing, since they are based on small samples. Yet the home bias in the playoffs, and the way in which it seems to change as a series progresses, is troubling, and worthy of further inquiry.