In the book Essentials of Marketing Research, William R. Dillon, Thomas J. Madden, and Neil A. Firtle discuss the relationship between delivery time and computer-assisted ordering. A sample of 40 firms shows that 16 use computer-assisted ordering, while 24 do not. Furthermore, past data are used to categorize each firm's delivery times as below the industry average, equal to the industry average, or above the industry average. The results obtained are given in the table below.
A Contingency Table Relating Delivery Time and Computer-Assisted Ordering
Computer-Assisted Ordering
Below Industry Average
Delivery Time
Equal to Industry Average
Above Industry Average
Row Total
No
4
12
8
24
Yes
10
4
2
16
Column total
14
16
10
40
(a) Test the hypothesis that delivery time performance is independent of whether computer-assisted ordering is used. What do you conclude by setting Ī± = .05?
(b) Verify that a chi-square test is appropriate.
(c) Is there a difference between delivery-time performance between firms using computer-assisted ordering and those not using computer-assisted ordering?