The EPA has stipulated that the Pollution Standard Index (PSI) for clean air standards is to average no more than 100. A random sample of nine days for the city of Acorn showed PSI readings of 144, 85, 90, 120, 150, 105, 93, 130, and 115. Assume the population of PSI readings is highly nonnormal. The EPA wants to determine if there is significant evidence to conclude that Acorn's air is dirtier than the stipulated clean air standards. Which one of the following tests is appropriate for this problem?
A) Wilcoxon signed ranks test
B) Wilcoxon rank sum test
C) sign test
D) Kruskal-Wallis test
E) Spearman's rank correlation test

Question

Quizplus · Accepted Answer

With a small sample and belief that the sample population is highly skewed, the sign test is the appropriate test to use.

The EPA Has Stipulated That the Pollution Standard Index (PSI)