Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 1

Question 1

A researcher observes that cities with more coffee shops have higher average incomes.
The researcher concludes that opening more coffee shops causes income to rise.
What is the primary flaw in this reasoning?

Accepted Answer

Correlation does not imply causation; a confounding variable may explain both.

Answer

The researcher used too small a sample.

Answer

The researcher should have used a randomized experiment instead of a survey.

Answer

Income data is unreliable in observational studies.

Question 2

A study randomly assigns 200 volunteers to two groups: Group A takes a vitamin supplement daily and Group B takes a placebo for 6 months. At the end, Group A reports significantly fewer colds. What conclusion is best supported?

Accepted Answer

The supplement may cause a reduction in colds among people similar to those in this study.

Answer

All adults who take this supplement will get fewer colds.

Answer

The supplement definitely cures colds for all populations.

Answer

The placebo group's results are invalid because they were deceived.

Question 3

A school district surveys 500 randomly selected students across all its schools about their reading habits and finds that students who read more also have higher GPA. Can the district conclude that reading more causes higher GPA?

Accepted Answer

No, because this is an observational study and causation cannot be inferred from correlation.

Answer

Yes, because the sample was randomly selected.

Answer

Yes, because a large random sample always establishes causation.

Answer

No, because GPA is not a reliable measure of academic performance.

Question 4

Researchers conduct a study in which participants are randomly assigned to eat breakfast or skip it, then measure their morning productivity for 4 weeks. The breakfast group showed significantly higher productivity. Which conclusion is best supported?

Accepted Answer

For people similar to study participants, eating breakfast likely causes higher morning productivity.

Answer

Eating breakfast is the cause of higher productivity in the general population.

Answer

All people who eat breakfast will be more productive.

Answer

Skipping breakfast is correlated with lower productivity for all adults worldwide.

Question 5

A nutritionist conducts an observational study of 1,000 adults and finds that those who eat fish twice a week have lower rates of heart disease. Which of the following is the most appropriate conclusion?

Accepted Answer

There is an association between eating fish and lower rates of heart disease in this sample.

Answer

Eating fish twice a week causes lower rates of heart disease.

Answer

All adults should eat fish twice a week to prevent heart disease.

Answer

Fish consumption is the single most important factor in preventing heart disease.

Question 6

A medical study randomly selects 300 patients from a clinic in one city, then randomly assigns half to a new treatment and half to standard care. The new treatment shows better outcomes. To which population can the results be most validly generalized?

Accepted Answer

Patients similar to those at this clinic who would be eligible for the treatment

Answer

All patients worldwide with this condition

Answer

Only the 300 patients in the study

Answer

All patients in the city

Question 7

A study finds that people who own pets have lower blood pressure. A journalist writes: 'Owning a pet reduces blood pressure.' Which error did the journalist make?

Accepted Answer

Concluding causation from an observational association

Answer

Confusing the independent and dependent variables

Answer

Misreporting the direction of the relationship

Answer

Using too small a sample for the study