But this isn't exactly what you might think – that zip code point is key. The HLDI isn't tallying the number of crashes around the stadium, but the number of cars that are insured in areas near the stadium that get in crashes anywhere. That's what makes it intriguing that the claim rate for those cars is 9.4 percent higher when the home team loses. Even when the home team wins the crash rate goes up, but only by 3.2 percent.
If we accept that the average car trip in the USA is about nine miles and that a large percentage of trips are less than two miles (one estimate is 40 percent), factoring in the huge amount of traffic around most stadiums during the season would lead us to believe that it plays a role in these numbers even if the HLDI didn't take account of where crashes happened. Come the pre-season this year, if you live near the field you might want to save your tailgating for after the game, give all those other raucous visiting winners and dejected home fans folks a chance to skedaddle. The press release below has a few more details.
ARLINGTON, Va., January 20, 2015 - The rate of collision claims from ZIP codes around NFL stadiums is higher on days when the home team loses or ties than when it wins, a new study from the Highway Loss Data Institute (HLDI) shows.
HLDI analysts looked at collision claims for ZIP codes in which the 31 NFL stadiums are located, as well as adjacent ZIP codes. Claim frequency was higher on home game days, compared with other days. The effect was especially pronounced in the ZIP codes where the stadiums are located, though it was also present in the surrounding ZIP codes.
In HLDI's claims data, the ZIP codes reflect the vehicle's garaging location, and not the location of the crash. Thus, crashes involving the vehicles of people who live elsewhere and drove into the ZIP code for the game aren't included. In addition, some crashes of vehicles garaged near the stadium could have taken place elsewhere. Nevertheless, the pattern of increased claim frequency on home game days is probably connected to higher traffic volumes around the stadiums on those days.
On days when the home team won, the rate of collision claims was 3.2 percent higher than on days without a home game. On days when the team lost or tied, the claim rate was 9.4 percent higher than on days without a home game. Only the increase for a loss or tie was statistically significant.
"The game day effect was much more pronounced at some stadiums than at others," says HLDI Vice President Matt Moore. "This may point to differences in policing and traffic management strategies, which could present opportunities for improvement."