*9. Is one Internet search engine more efficient than another? You ask each of seven student volunteers to find information on a specific topic using one search engine (search 1) and Training Program 1: X1 ¼ 56:3 SS1 ¼ 538 Training Program 2: X2 ¼ 44:3 SS2 ¼ 354 r12 ¼ þ:04 Exercises 315 then to find information on the same topic using a competing search engine (search 2).

Four of the students use search 1 first, whereas the remaining three use search 2 first. The results (in seconds) are as follows:

Student Search 1 Search 2 A 25 26 B 53 55 C 67 71 D 74 80 E 94 93 F 93 105 G 110 120 Using the direct-difference method:

(a) Set up the statistical hypotheses.

(b) Compute D, SSD, and sD

(c) Perform the test (a ¼ :05).

(d) Draw final conclusions.