An organization wants to know if drinking caffeinated coffee causes hyperactivity in college students. To test their research question, they offered students free coffee to students throughout the term in exchange for participating in the study. Researchers intentionally balanced participating students into groups by the student’s year, major, and gender. One group received regular coffee and the other received decaffeinated coffee. Students obtained their free coffee at will from the research stations and through the day used an app to track how hyperactive they felt.a) What are the independent variables?b) What is the dependent variable?c) What kind of study design is this?d) What kind of sampling method is being used?

a) An independent variable refers to the object(s) or variable that is been measured which is not affected or changed by other variables. Rather, the independent variable affects or changes other variables. That is why drinking caffeinated coffee falls under the independent variable.

b) The dependent variable on other hand is a variable that can be affected or changed by the independent variable. That is why hyperactivity falls under the dependent variable.

c) Noteworthy is the fact that in an experimental study a researcher usually alters the level of the independent variable [the caffeinated coffee]. This is evident in this case because we are told, "One group received regular coffee and the other received decaffeinated coffee."

d) The kind of sampling method used is the Non-Probability Sampling Method because they [the students] which formed the population were not randomly selected, but "intentionally balanced" into groups by the student’s year, major, and gender.