Sixty students were randomly divided into two groups as part of a study ono the effects of alcohol on reaction time. Each member of one group consumed a specified amount of alcohol and members of the other group had a non-alcoholic beverage. The reaction time of both groups were measured before and after taking the beverage/alcoholic drink.

1. What is the independent variable?

a. amount of alcohol

b. reaction time

c. one student

d. sixty students

2. What is the dependent variable?

a. amount of alcohol

b. reaction time

c. one student

d. sixty students

3. What is the experimental unit?

a. amount of alcohol

b. reaction time

c. one student

d. sixty students

4. Which of the following is/are potential extraneous variable/s in this study?