Question: For each of the following hypothetical scenarios, state whether selection or assignment is being described. Is the method of selection or assignment random? Explain your answer.
a. A study of the services offered by counseling centers at Canadian universities studied 20 universities; every Canadian university had an equal chance of being in this study.
b. In a study of phobias, 30 rhesus monkeys were either exposed to fearful stimuli or not exposed to fearful stimuli. Every monkey had an equal chance of being placed in either of the exposure conditions.
c. A study of cell phone usage recruited participants by including an invitation to participate in their cell phone bills.
d. A study of visual perception recruited 120 Introduction to Psychology students to participate.