Chapter 8.3, Problem 8.37ACI

Taking “power naps” during work breaks. Lack of sleep costs companies about $13 billion a year in lost productivity, according to the National Sleep Foundation. In recognition of this problem, many companies now make quiet rooms available for employees to take “power naps” during work breaks (U.S. News & World Report, November 15, 2010). Consider a major airline that encourages reservation agents to nap during their breaks. The accompanying table lists the number of complaints received about each of a sample of 10 reservation agents during the 6 months before naps were encouraged and during the 6 months after the policy change.

1. a. Do the data present sufficient evidence to conclude that the new napping policy reduced the mean number of customer complaints about reservation agents? Test using α: — .05.
2. b. What assumptions must hold to ensure the validity of the test?
3. c. What variables, no: controlled in the study, could lead to an invalid conclusion?

Operator	Before Policy	After Policy
1	10	5
2	3	0
3	16	7
4	11	4
5	8	6
6	2	4
7	1	2
8	14	3
9	5	5
10	6	1