Question: Many people were appalled, but not surprised, when the New York Times reported that nine Jet Blue airplanes full of angry passengers sat for six hours on the tarmac at JFK International Airport when an ice storm hit New York earlier this spring. (The passengers were then told the flights were cancelled and they were deposited back at the gate). It has become the norm to expect that there will be delays when we travel. But how bad is the problem? Are some airlines doing better than others? Does it make a difference when you fly, or where you fly? The data sets provided for you in the exam come from the US Bureau of Transportation Statistics. By the way, the bureau defines a delay as a plane arriving, or leaving, more than 15 minutes behind schedule.

Let’s begin with the question of whether or not we really do experience regular delays when we fly. I would argue that if 25% of flights were delayed on average (1 out of every 4 flights), that would surely be considered a regular occurrence. Using this hypothesized mean, are delayed arrivals a regular occurrence at US airports? What about delayed departures?