Airlines have increasingly outsourced the maintenance of their planes to other companies. A concern voiced by critics is that the maintenance may be less carefully done so that outsourcing creates a safety hazard. In addition, flight delays are often due to maintenance problems, so one might look at government data on percent of major maintenance outsourced and percent of flight delays blamed on the airline to determine if these concerns are justified. This was done, and data from 2005 and 2006 appeared to justify the concerns of the critics. Do more recent data still support the concerns of the critics? Here are data from 2014:

AirlineOutsource percentDelay percentAirlineOutsource percentDelay percentAlaska51.0

10.35

Jet Blue68.4

19.93

American29.4

20.32

Southwest58.2

28.47

Delta36.7

14.48

United52.6

23.46

Frontier46.3

21.42

US Airways54.3

13.68

Hawaiian78.4

5.06

Find the correlation