Suppose we want to study how a drug affects someone's happiness.It is difficult to make a direct observation of how happy someone is, so which of the following would be the best proxy variable?

Question

Quizplus · Accepted Answer

Frequency of smiling is the best proxy variable as it is directly related to one's level of happiness. A person is more likely to smile when they are happy, and less likely to smile when they are not. Time spent exercising, use of pain medication, alcohol consumption, and frequency of social interaction are not necessarily directly related to a person's level of happiness.

Suppose We Want to Study How a Drug Affects Someone's