Question

Refer to Problem 6.42 which deals with lung capacity of rats exposed to ozone. Note: For consistency, please calculate the differences as After – Before for all questions.

'Rat','Before','After'
1,8.7,9.4
2,7.9,9.8
3,8.3,9.9
4,8.4,10.3
5,9.2,8.9
6,9.1,8.8
7,8.2,9.8
8,8.1,8.2
9,8.9,9.4
10,8.2,9.9
11,8.9,12.2
12,7.5,9.3

A. Are the differences normally distributed? Support your answer by including a qqplot of differences in your assignment.

B. Is there sufficient evidence to support that ozone exposure increases lung capacity? Use the paired t-test with α=0.05. State the hypotheses, test statistic, p-value and conclusion. (4 pts)

C. Estimate the size of the increase in lung capacity after exposure and construct a 95% tbased CI. Note: provide a standard “two-sided” CI here.

D. Rerun the test from part B using the Wilcoxon Paired (Signed Rank) test. Give your p-value and conclusion. Use the wilcoxsign_test() function from the coin package with distribution = “exact”. Remember to use a one-sided alternative. (4 pts)

Answer 1