Chapter 9.3, Problem 38E

Adding computerized medical images to a database promises to provide great resources for physicians. However, there are other methods of obtaining such information, so the issue of efficiency of access needs to be investigated. The article “The Comparative Effectiveness of Conventional and Digital Image Libraries”(J. of Audiovisual Media in Medicine, 2001: 8–15) reported on an experiment in which 13 computer proficient medical professionals were timed both while retrieving an image from a library of slides and while retrieving the same image from a computer database with a Web front end.

Subject	1	2	3	4	5	6	7
Slide	30	35	40	25	20	30	35
Digital	25	16	15	15	10	20	7
Difference	5	19	25	10	10	10	28
Subject	8	9	10	11	12	13
Slide	62	40	51	25	42	33
Digital	16	15	13	11	19	19
Difference	46	25	38	14	23	14

a. Construct a comparative boxplot of times for the two types of retrieval, and comment on any interesting features.

b. Estimate the difference between true average times for the two types of retrieval in a way that conveys information about precision and reliability. Be sure to check the plausibility of any assumptions needed in your analysis. Does it appear plausible that the true average times for the two types of retrieval are identical? Why or why not?