Chapter 11.2, Problem 36E

To determine

To explain why this test is incorrect.

Explanation of Solution

In the question it is given that, the researchers want to know that does eating chocolate trigger headaches. To find out, women with chronic headaches followed the same diet except for eating chocolate bars and carob bars that looked and tasted the same. Each subject ate both chocolate and carob bars in random order with at least three days between. And the table of the same is given in the question. Thus, the researchers carried out a chi-square test on this table if the two types of bar differ in triggering headaches. Therefore, this test is incorrect because each row contains data about the same subjects and thus the rows are not independent of each other. Since the Independent requirement is not satisfied, we cannot apply the chi-square test.