Question

for his statistics class experiment, research j. gilbert decided to study how parents income affects childrens performance on standardized tests like sat. he proposed to collect information from a random sample of test takers and examine the relationship between parental income and sat score.
a) is this an experiment? if not, what kind of study is it?
b) if there is a relationship between parental income and sat score, why cant we conclude that differences in score are caused by differences in parental income?

a) is this an experiment? if not, what kind of study is it?
a. this is an experiment.
b. this is not an experiment. there are no manipulated factors. this is a retrospective study.
c. this is not an experiment. there are no manipulated factors. this is a prospective study.
d. this is not an experiment. there are no manipulated factors. this is an observational study.

b) if there is a relationship between parental income and sat score, why cant we conclude that differences in score are caused by differences in parental income?
a. the results are not valid because no control treatment is specified.
b. causation cannot be concluded from observational data.
c. superfluous variation may be causing the relationship because blocking was not used.
d. results may be biased because blinding was not used.

Explanation:

Part (a)

To determine if it's an experiment, we check for manipulated factors. In this study, J. Gilbert is observing the relationship between parental income (a naturally occurring variable) and SAT scores without manipulating any factor (like assigning different income levels to parents). An observational study involves observing and measuring variables without intervention, while an experiment requires manipulating an independent variable. Since there's no manipulation, it's an observational study. Option D correctly states this.

Causation from observational data is not valid because observational studies only show associations. Other confounding variables (like parental education, study habits of students, etc.) could be influencing both parental income and SAT scores. Option B correctly explains that causation can't be concluded from observational data, as experiments (with random assignment) are needed to establish causation.

Answer:

D. This is not an experiment. There are no manipulated factors. This is an observational study.

Part (b)