Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 2

Question 1

Researchers want to determine whether a new tutoring program improves standardized test scores. They randomly assign 150 students to receive tutoring and 150 students to a control group with no tutoring, then compare scores. Why is random assignment important in this study?

Accepted Answer

It controls for confounding variables by balancing them across groups on average.

Answer

Random assignment distributes known and unknown confounding variables roughly equally between groups, allowing differences in outcomes to be attributed to the treatment.

Question 2

A study observes that neighborhoods with more parks have lower obesity rates. A city planner concludes that building more parks will reduce obesity. Which type of additional evidence would most strengthen the claim that parks reduce obesity?

Accepted Answer

A randomized experiment in which some neighborhoods are randomly assigned new parks

Answer

Only a randomized experiment with random assignment can establish causation; more observational evidence strengthens association but not causation.

Question 3

A researcher surveys 400 college students randomly selected from one university about social media use and GPA. The results show a negative association. Which statement correctly describes what the researcher can conclude?

Accepted Answer

There is a negative association between social media use and GPA among students at this university.

Answer

Because this is an observational study with a sample from one university, the results can identify an association in that population but cannot establish causation or broad generalizability.

Question 4

A clinical trial randomly assigns 500 patients to either a new drug or a placebo. The drug group shows significantly fewer symptoms. A doctor generalizes this to all patients with the condition. What concern is most valid?

Accepted Answer

The study can only be generalized to patients similar to those who participated in the trial.

Answer

Even with random assignment, generalizability is limited to populations represented by the study participants; the doctor's broad generalization may be unwarranted.

Question 5

An education researcher randomly assigns 40 classrooms to use a new math curriculum and 40 to use the standard curriculum. At year-end, the new curriculum classrooms score significantly higher. What is the most valid conclusion?

Accepted Answer

The new curriculum causes higher math scores in classrooms like those in the study.

Answer

Random assignment of classrooms supports a causal conclusion for classrooms similar to those in the study, though it may not generalize to all possible classroom environments.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 2