On the Wells report

In the current "Deflategate" controversy, the New England Patriots have been accused of illicitly deflating footballs before the start of their 2015 American Football Conference championship game against the Indianapolis Colts. The National Football League and the lawyers it hired have produced a report - commonly known as the "Wells report" - that has been used to justify penalties against the Patriots and quarterback Tom Brady. Although the Wells report finds that the Patriots footballs declined in pressure significantly more than the Colts balls in the first half of the game, our replication of the report's analysis finds that it relies on an unorthodox statistical procedure at odds with the methodology the report describes. It also fails to investigate all relevant scenarios. In addition, it focuses only on the difference between the Colts and Patriots pressure drops. Such a difference, however, can be caused either by the pressure in the Patriots balls dropping below their expected value or by the pressure in the Colts balls rising above their expected value. The second of these two scenarios seems more likely based on the absolute pressure measurements. Logistically, the greater change in pressure in the Patriots footballs can be explained by the fact that sufficient time may have passed between halftime testing of the two teams' balls for the Colts balls to warm significantly, effectively inflating them.