Question: A fluvial geo morphologist is interested in whether there is a change in the dissolved oxygen levels in a river before and after weed removal. Dissolved oxygen levels were measured at 10 different sites, before and after the removal of vegetation from the stream bed.
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a. Conduct a matched-pairs test to determine whether there is a change in dissolved oxygen levels following weed removal.
b. Suppose the hypothesis being tested is that dissolved oxygen levels have declined. How would this change your results?
c. If you hadn't noticed that the data were matched pairs, what might you have concluded in a simple difference-of-means test?