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

Observational studies can identify associations but cannot establish causation because confounding variables (e.g., city wealth) may explain both variables.

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

Randomized experiments support causal conclusions, but the results can only be generalized to populations similar to those in the study.

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

Even with random sampling, observational studies cannot establish causation because subjects were not randomly assigned to treatments; a third variable could explain the relationship.

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

Random assignment supports a causal conclusion, but generalizability is limited to populations similar to those studied.

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

An observational study can only identify associations, not causal relationships, since participants were not randomly assigned to a diet.

Bluebook SAT Practice Test Practice Test

Bluebook SAT Practice Test Practice Test

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