Rachel is studying the effects of classical music exposure on math learning. She recruits 10 sets of twins and assigns one child in each pair to listen to classical music for an hour a day, and assigns the other child to listen to an audio book. At the end of a week, she gives each child a math lesson on tape and asks them to complete a math test. Rachel hypothesizes that classical music exposure will help math learning. What of the following is true about her study?
A) Rachel should use the independent samples t-test to account for potential subject mortality.
B) Rachel is able to eliminate the variance from individual differences due to her study design.
C) Since Rachel knows the population standard deviation, she should use the z-test.
D) Rachel is able to eliminate the variance from random chance due to her study design.

Question

Quizplus · Accepted Answer

By assigning one child in each pair to listen to classical music and the other to an audio book, Rachel is essentially controlling for individual differences such as genetics, upbringing, and environmental factors. This design allows her to isolate the effect of the independent variable (classical music exposure) on the dependent variable (math learning), and thus eliminates individual differences as a source of variance. However, Rachel cannot completely eliminate variance from random chance or subject mortality, and thus cannot use z-test or independent samples t-test.

Rachel Is Studying the Effects of Classical Music Exposure on Math