Refer to Exercise 6.46. Answer the following questions using the combined data for both depths.

a. Use the Wilcoxon rank sum test to assess whether there is a difference in population abundances between the sites within and outside the oil trajectory. Use α = .05.
b. What are the required conditions for the techniques used in part (a)?
c. Are the required conditions satisfied?
d. Discuss any differences in the conclusions obtained using the t procedures and the Wilcoxon rank sum test.

Within Oil Trajectory Outside Oil Trajectory Depth 40 m 5,124 2904 3600 2,880 2,578 4146 1,048 1,336 394 7,370 6,762 744 1,874 Depth 100 m 3228 2.032 3256 3,816 2.438 4897 1346 1,676 2,0 2224 1.234 1598 2,182