Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 16

Question 1

A study randomly assigns 120 employees to a four-day workweek and 120 to a five-day workweek for 3 months, then measures productivity and job satisfaction. The four-day group scores higher on both. What conclusion is best supported?

Accepted Answer

A four-day workweek caused higher productivity and job satisfaction compared to a five-day workweek in this experiment.

Answer

Random assignment supports the causal conclusion that the four-day workweek caused higher productivity and satisfaction in this study population and timeframe.

Question 2

An observational study finds that children who own more books at home have higher reading scores. A librarian claims that donating books to low-income homes will raise reading scores. What is the most significant concern with this conclusion?

Accepted Answer

Homes with more books may also have parents who read more to their children, higher parental education, and more verbal interaction—confounding the effect of books alone.

Answer

The number of books in the home is strongly correlated with parental education and reading habits, which are the true drivers of reading scores in this observational data.

Question 3

A controlled experiment randomly assigns 500 overweight adults to either a low-carbohydrate diet or a low-fat diet for 6 months. The low-carb group loses significantly more weight. A nutritionist says: 'This proves low-carb diets are superior for everyone.' What is the most important limitation of this claim?

Accepted Answer

The study participants may not represent all overweight adults, so the results may not apply to everyone.

Answer

Even with random assignment supporting a causal claim, the sample's characteristics determine generalizability; 'everyone' is too broad based on a single trial.

Question 4

A school researcher observes that students who sit in the front rows earn higher grades than those who sit in the back. The researcher recommends assigning all struggling students to front seats. What is the primary flaw in this recommendation?

Accepted Answer

Students who choose front seats may be more motivated and engaged regardless of where they sit, creating self-selection confounding.

Answer

Students who voluntarily sit in front are likely more motivated and attentive; moving struggling students to the front may not replicate the effect if motivation is the real driver.

Question 5

A randomized study finds that patients who received cognitive behavioral therapy (CBT) alongside medication improved more than patients who received medication alone. The study recruited patients from mental health clinics in three states. To which population can the findings be most validly generalized?

Accepted Answer

Patients with similar diagnoses receiving care at comparable mental health clinics

Answer

The random selection from mental health clinics in three states supports generalization to patients at similar clinics; random assignment supports the causal claim.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 16