Question

Should the drinking age should be lowered to age 18? To address this question, researchers randomly select 1000 US adults: two hundred and fifty 18-24-year-olds, two hundred and fifty 25- 40-year-olds, two hundred and fifty 40-55-year-olds, and two hundred and fifty over 55-year-olds. Overall, 73% of those surveyed said no, the drinking age should not be lowered to age 18. The survey reported a margin of error of ±4%.

a. What is the confidence interval and how should it be interpreted?

b. How would you respond to someone who claims the majority of US adults are in favor of lowering the drinking age?

c. Is this an experiment or observational study? Explain.

d. Name and describe one type of bias that could be present in this study.

Answer 1

a) Confidence interval is a range of values so defined that there is a specified probability that the value of a parameter lies within it. For example, we use a 95% confidence level then we can say that 95% times of the case the parameter considered value will lie in the confidence interval range that we get.

b) I would respond that it is wrong according to the data observed, and that 73% are against it, rather than in the favor of it.

c) This is an observational study. In an observational study, we measure or survey members of a sample without trying to affect them. In a controlled experiment, we assign people or things to groups and apply some treatment to one of the groups, while the other group does not receive the treatment.

d) Sampling bias can be there, as we are taking samples of different age, but majority of the drinking population may be in a particular age range or ranges.