WestJet Airlines is able to keep fares low in part because of relatively low maintenance costs on its airplanes. One of the main reasons for the low maintenance costs is that WestJet flies mainly one type of aircraft, the Boeing 737. However, WestJet flies three different versions of the 737. Suppose WestJet decides to conduct a study to determine whether there is a significant difference in the average annual maintenance costs for the three types of 737s used.
a. State an independent variable for such a study.
b. What are some of the levels or classifications that might be studied under this variable?
c. Give a dependent variable for this study.