By now it is almost impossible to not have heard some opinion about the latest National Football League (NFL) scandal, universally dubbed Deflategate (continuing the time-honored tradition of affixing the particularly grotesque –gate to perfectly good English words). To review, the NFL accused the New England Patriots of intentionally deflating footballs below the regulation bound on pressure during the team’s game against the Indianapolis Colts in the AFC Championship Game, a contest they handily won 45-7.
While impassioned fans and detractors have hurled insults left and right throughout the controversy, I focus purely on possible sources of error in the NFL’s investigative report, the Wells report, in my analysis rather than enter the political back-and-forth between football allegiances. What is important to note here is that different teams and their quarterbacks hold different preferences for the pressure of their footballs. According to Chad Orzel ’93, associate professor of physics at Union College, low-pressure footballs are potentially easier to manipulate and catch when accompanied by wet and ambient playing conditions.
Critics of the Patriots argue that the team played with an unfair competitive advantage. Drawing from physics, the relevant principle here is the ideal gas law (Kinetic Molecular Theory of Gases) which states: PV = nRT, where P is pressure of a gas, V is volume, n is the number of gas molecules, R is a constant and T is the absolute temperature.
When footballs are brought outside from warmer indoor temperatures, we expect a drop in T, which should be compensated for on the other side of the equation by a drop in P. We can assume V is constant because the extent of the football is roughly constant. The crux of the NFL’s report is that the Patriots’ footballs were lower in pressure compared to the Colts’ footballs that were also brought outside from a warmer environment. Therefore, the report argues, purposefully deflating the balls before the game would explain the discrepancy in air pressure of the two sets of footballs.
As good scientists, we must look at possible sources of error and problems in experimental methodology that could dilute how much we can trust the Wells report’s findings. A New York Times article titled “Deflating Deflategate” published on June 12 argues that the Colts’ footballs were actually too high in pressure: “At halftime, NFL officials measured the pressure of ‘only a sample’ of the Colts’ balls (four out of 12) before they ran out of time; the second half of the game was about to begin. This implies that the Colts’ balls sat in the warm room where they were to be measured – and thus increased in pressure – for almost the entirety of halftime before being measured.”
By contrast, 11 of the Patriots’ balls were measured by halftime, implying that they were measured at a lower temperature – and pressure. This kind of explanation might call some of the report findings into question. A sciencenews.org article titled “Deflategate favored foul play over science” published on June 18 pointed out another possible explanation for the discrepancy. Apparently, the NFL used two different gauges that differed by 0.4 psi in their measurement – a significant possible source of error that is not noted in the data collection report.
While everyone agrees on the basic physics governing how pressure might change inside a football, it is the experimental methodology of the NFL that must be called into question. Shoddy data collection and lack of multiple trials makes it much harder to explain away sources of error. While many Americans were concerned about whether the Patriots were at fault, the Wells report brings a larger issue into the spotlight; data must be collected rigorously to be able to support an argument, whatever that claim might be.