Scenario A: A professor is interested in studying whether consuming caffeine at different times of day disrupts sleep quality. She instructs her participants to take a caffeine pill at noon on Monday, 5pm on Wednesday, and at 9pm (right before bed) on Saturday and then measures their sleep quality using an apparatus that calculates how long it takes them to fall asleep each night.
1. What is the independent variable?
2. How many levels are there for the independent variable?
3. What is the dependent variable?
4. What is the confound?
5. How could the confound be fixed?