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

People who walk daily will always have lower blood pressure than those who are sedentary.

Answer

The results can be applied to all adult populations worldwide.

Answer

The reduction in blood pressure is due to placebo effects.

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

The journalist should have counted bicycle lanes per resident rather than total lanes.

Answer

Traffic fatality data is not a reliable measure.

Answer

The study should have been conducted over a longer period.

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

All adults worldwide with sleep problems

Answer

Only the 500 participants in the study

Answer

All adults who voluntarily seek sleep therapy

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

The study did not control for the type of extracurricular activity.

Answer

Graduation rates are not a valid outcome measure.

Answer

The sample of students was too small to draw conclusions.

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

All students will improve their math scores if they use this tutoring program.

Answer

The tutoring program is the best math intervention ever designed.

Answer

Math scores improve whenever students receive any form of additional instruction.

Question 6

A public health report notes that counties with higher rates of fast food restaurant density have higher obesity rates. An advocacy group concludes that fast food restaurants cause obesity. What is the primary weakness in this conclusion?

Accepted Answer

The county-level association is observational and may reflect socioeconomic or cultural confounders rather than a direct causal effect.

Answer

The study measured the wrong type of restaurant.

Answer

The study should have used individual-level data.

Answer

Obesity rates are not accurately measured at the county level.

Question 7

A study randomly assigns 100 participants to write in a gratitude journal daily and 100 to write a neutral diary for 6 weeks, then measures happiness. The gratitude group scores significantly higher. What is the MOST valid conclusion?

Accepted Answer

The gratitude journaling practice caused higher happiness scores in this experiment.

Answer

Everyone who keeps a gratitude journal will become happier.

Answer

Neutral diary writing is harmful to well-being.

Answer

The results would hold for any journaling format.