In a study conducted to determine the role that sleep disorders play in academic performance, researcher Jane Gaultney conducted a survey of 1845 college students. The students completed a survey to determine if they had a sleep disorder (such as narcolepsy, insomnia, or restless leg syndrome). Of the 503 students with a sleep disorder, the mean grade point average was 2.65 with a standard deviation of 0.87. Of the 1342 students without a sleep disorder, the mean grade point average was 2.82 with a standard deviation of 0.83.

(a) What is the response variable in this study? What is the explanatory variable?

(b) Is there evidence to suggest sleep disorders adversely affect one’s GPA at the α = 0.05 level of significance?