Refer to Example 14 concerning suspended solids in effluent from a treatment plant. Take the natural logarithm of each of the measurements and then take the difference.

(a) Construct a 95% confidence interval for \(\mu_{D}\).

(b) Conduct a level \(\alpha=0.05\) level test of \(H_{0}: \mu_{D}=\) 0 against a two-sided alternative. Verify that the conclusion is the same as that obtained from the confidence interval.

(c) Make a dot diagram of these differences and decide if the transformation has essentially removed the outliers.

Data From Example 14

Data From Example 13

EXAMPLE 14 Exploring the form of dependence With reference Example 13, find a pattern in the departure from independence.