a. Discuss the veracity of the following statement: “The oil spill did not adversely affect the population abundance; in fact, it appears to have increased the population abundance.”
b. A possible criticism of the study is that the six sites outside the oil trajectory were not comparable in many aspects to the seven sites within the oil trajectory. Suppose that the researchers had data on population abundance at the seven within-trajectory sites prior to the oil spill. What type of analysis could be used on these data to evaluate the effect of the oil spill on population abundance? What are some advantages to using these data rather than the data in Exercise 6.46?
c. What are some possible problems with using the before and after oil spill data in ­assessing the effect of the spill on population abundance?