Unit B-3: Practice Now

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Practice Materials for 'The Basics' 3

A travel agent wishes to advise a client traveling to Seattle and Phoenix. Both cities are served by Alaska and American West. The airlines reported the flight on-time arrival data in this table. Alaska, however, claimed to have a better on-time arrival record than American West in both cities. How can this be?

On Time Flights	Alaska	American West
On time	2062	5041
Total	2379	5517
On Time	86.6%	91.4%

Here is a table of on time performance for Phoenix and Seattle:

On time Fights	Alaska		American West
	On Time	Total	On Time	Total
Phoenix	221	223	4840	5255
Seattle	1841	2146	201	262

a. Calculate the on-time arrival rate for each airline in each city. Who has the better record?
(Stan )Radio: a. Can't tell b. Alaska c. American West

Possible answer

b. What feature of the on-time flight data caused these results?
(Stan )Radio: a. the airline b. the arrival city c. can't say

Possible answer

c. What is the name for this situation?
(Stan )Radio: a. Independent Events b. Simpson's Paradox c. Bias

Possible answer

d. What is the lurking variable in this example?
(Stan )Radio: a. month of year b. time of day c. arrival city

Possible answer