A cable TV company was interested in making its operation more efficient by cutting down on the distance between service calls while still maintaining at least the same level of service quality. A treatment group of 18 repairpersons was assigned to a dispatcher who monitored all the incoming requests for cable repairs and then provided a service strategy for that day's work orders. A control group of 18 repairpersons was to perform their work in a normal fashion€”that is, by providing service in roughly a sequential order as requests for repairs were received. The average daily mileages for the 36 repairpersons are recorded here:

a. What are the populations of interest in this study?
b. Is there significant evidence that the treatment group had a smaller average daily mileage than the control group? Use μ = .05.
c. What is the level of significance of your test?
d. Estimate the difference in the average daily mileage for the treatment and control groups using a 95% confidence interval.
e. There are three possible procedures that could be applied to answer the questions in parts (b), (c), and (d). Which of these procedures appears to be the most valid?

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Treatment Group 62.2 95.8 85.2 97.1 109.5 63.9 79.3 97.9 87.9 70.2 101.7 88.2 83.2 91.5 86.7 94.6 99.7 99.1 82.2 96.6 99.7 182.9 193.2 95.1 84.1 90.1 101.1 85.6 105.3 92.4 89.3 98.6 886 89.5 92.9 87.3 Control Group