Airline Arrivals

The exercise examines the relationship between the destination city (Phoenix and Seattle) and the number of arrivals on time for Alaska and America West Airlines in 1987. Click on Data under Chapter 1 in the left panel and then select Open remote ... under the File menu in the right panel. Select arrivals.xml from the Open File Dialog and click OK. Note that On-time? is assigned the Y role, Destination the X role, and Airline the Z role by default, whereas Freq is assigned the Frequency role. Select xy|z from the Graph menu. Open the contingency table by clicking on the Contingency table sub-menu item in the Plot menu. Note that the values (percentages) in the contingency table change depending on the selected value of the conditioning Airline variable (Alaska or AmerWest). However, you may need to click on the continency table to activate the changes. Use the Display menu items to answer the following questions.

  1. Find the percentage of on-time arrivals to Phoenix for Alaska Airlines and for America West Airlines. Which airline had a better on-time percentage?
  2. Find the percentage of on-time arrivals to Seattle for Alaska Airlines and for America West Airlines. Which airline had a better on-time percentage.
  3. Which airline had a better on-time percentage, combining all flights to Seattle and Phoenix?
  4. How do you explain the answer to Question 3, given the answers to Questions 1 and 2?
  5. What is the overall percentage of on-time arrivals to Seattle, combining the two airlines? Hint: you need to reverse the roles of Dest and Airline and repeat the analyzes.
  6. What is the overall percentage of on-time arrivals to Phoenix, combining the two airlines?