An educational software company wants to compare the effectiveness of its computer animation for teaching about supply and demand curves with that of a textbook presentation. The company tests the economic knowledge of a number of first-year college students, then divides them into two groups. One group uses the animation, and the other studies the text. The company retests all the students and compares the increase in economic understanding in the two groups. This is an example of
a. an observational study.
b. an uncontrolled experiment.
c. a randomized comparative experiment.
What are the explanatory and response variables?
1. Explanatory variable
2. Response variable
The teaching method.
The change in the student's test score.