These data compare the on-time arrival performance of fights on American and Delta. The table shows the status of 17,064 arrivals during January 2006.

(a) On the basis of this initial summary, find the percentages (row or column) that are appropriate for comparing the on-time arrival rates of the two airlines. Which arrives on time more often?
(b) The next two tables organize these same fights by destination. The first shows arrival time and the second shows airline. Does it appear that a lurking variable might be at work here? How can you tell?

(c) Each cell of the following table shows the number of on-time arrivals for each airline at each destination. Is Destination a lurking factor behind the original 2 × 2 table?

Status On time Delayed American Delta 1,1769 416 3,343 1,536 Status On time Delayed Atlanta Las Vegas San Diego 11,512 3,334 786 181 1,007 244 Airline American Delta Atlanta Las Vegas San Diego 653 698 553 601 14,193 366 AirlineAtlanta Las Vegas San Diego American 497 Delta 11,015 561 478 446 308