Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 7

Question 1

A news headline reads: 'Students who eat lunch perform better in afternoon classes.' The data came from a study where students chose whether to eat lunch. Which of the following is most likely a confounding variable?

Accepted Answer

Overall health and family habits that affect both eating patterns and academic performance

Answer

Students from families that emphasize regular meals may also emphasize studying and routines, making family habits a confounding variable associated with both lunch-eating and academic performance.

Question 2

A pharmaceutical company randomly assigns 1,000 patients with high blood pressure to either a new medication or a placebo. After 6 months, the medication group shows a significant reduction in blood pressure. The company claims the medication is effective for all patients with high blood pressure. What is the most valid concern?

Accepted Answer

The study sample may not represent all patients with high blood pressure, such as those with other conditions.

Answer

Random assignment supports causation within the sample, but the sample's characteristics (e.g., age, comorbidities) may limit how broadly the results apply.

Question 3

Researchers observe that countries with more hospitals per capita also have longer life expectancy. They conclude that building more hospitals increases life expectancy. What is the most likely confounding variable?

Accepted Answer

National wealth, which increases both hospital capacity and access to food, education, and clean water

Answer

Wealthier nations can afford more hospitals and also have better nutrition, education, sanitation, and healthcare access — all of which increase life expectancy independently.

Question 4

A social scientist conducts an experiment by randomly assigning rural communities to receive a new community center and comparing crime rates to communities that did not receive one. After 2 years, crime rates are lower in communities with the center. What is the scope of the valid causal conclusion?

Accepted Answer

In rural communities similar to those studied, community centers likely cause lower crime rates.

Answer

Random assignment supports causation; the causal conclusion applies to rural communities similar to those in the study, not to all communities globally.

Question 5

A study surveys 800 teenagers about sleep habits and academic performance. Students who sleep 9 or more hours have higher GPA. A parent concludes that forcing teens to sleep 9 hours will improve their grades. Why is this conclusion flawed?

Accepted Answer

The association is from an observational study; factors like family structure and health may cause both more sleep and higher GPA.

Answer

Observational studies cannot establish that sleep causes higher GPA; structured home environments may promote both longer sleep and better academic habits.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 7