Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 10

Question 1

A study randomly assigns 200 adults to either a daily walking program or a sedentary control group for 8 weeks. The walking group shows significantly lower blood pressure. Which conclusion is best supported?

Accepted Answer

Daily walking appears to cause a reduction in blood pressure based on the randomized experiment.

Answer

Random assignment in a controlled experiment supports causal conclusions about the effect of walking on blood pressure within the study population.

Question 2

A journalist reports that cities with more bicycle lanes have fewer traffic fatalities per capita. The journalist concludes that adding bicycle lanes reduces traffic deaths. What is the most significant flaw in this reasoning?

Accepted Answer

The data are observational; other differences between cities (e.g., population density, traffic laws) could explain the relationship.

Answer

Without controlling for other city-level differences, the correlation between bicycle lanes and lower fatalities may reflect confounding variables rather than a causal effect of the lanes.

Question 3

Researchers randomly select 500 adults from a national registry, then randomly assign half to a new sleep therapy and half to standard care. The therapy group shows a significant improvement in sleep quality. To which group can the results be most validly generalized?

Accepted Answer

Adults similar to those in the national registry from which the sample was drawn

Answer

The random selection from a national registry allows generalization to the population represented by that registry; random assignment supports causal conclusions.

Question 4

A researcher finds that students who participate in extracurricular activities have higher graduation rates than those who do not. The researcher claims participation in extracurriculars causes higher graduation rates. What is the most important limitation of this claim?

Accepted Answer

Students who participate in extracurriculars may differ from non-participants in motivation, family support, or other factors that also affect graduation.

Answer

Participation in extracurriculars is self-selected; students who join activities may already have characteristics (higher motivation, better support) that predict graduation regardless of participation.

Question 5

A well-designed randomized controlled experiment finds that a specific tutoring program significantly raises math scores compared to a control group. Which of the following would be the most appropriate conclusion?

Accepted Answer

The tutoring program caused an increase in math scores for participants in this study.

Answer

A randomized experiment supports a causal claim within the study population, but generalizability and superiority over other programs require additional evidence.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 10