Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 9

Question 1

A study finds that students who eat breakfast score higher on standardized tests.
The researchers conclude that eating breakfast causes higher test scores.
What is the most significant flaw in this conclusion?

Accepted Answer

The study is observational and cannot establish causation because confounding variables may explain the relationship.

Answer

The study did not use a large enough sample.

Answer

The study should have used a placebo group.

Answer

The study only measured test scores and not other academic outcomes.

Question 2

A clinical trial randomly assigns 300 patients to receive either a new arthritis medication or a placebo for 12 weeks, and the medication group reports significantly less pain. What conclusion is best supported?

Accepted Answer

The new medication appears to cause a reduction in arthritis pain based on this randomized experiment.

Answer

The new medication is the best available treatment for arthritis pain.

Answer

Patients who take arthritis medication always report less pain.

Answer

The results can be generalized to all arthritis patients worldwide.

Question 3

Researchers observe that people who regularly attend concerts report higher life satisfaction than those who do not. A magazine concludes: 'Attending concerts improves life satisfaction.' What is the main limitation of this conclusion?

Accepted Answer

The study is observational; people who attend concerts may differ from non-attendees in other ways that affect satisfaction.

Answer

The study should have used a random sample of concert types.

Answer

The researchers should have measured concert attendance more precisely.

Answer

The conclusion is valid because the sample is large.

Question 4

Researchers want to study whether a new fertilizer increases crop yield. They randomly assign 50 plots of land to receive the new fertilizer and 50 plots to receive standard fertilizer, then measure yield at harvest. Why is random assignment important in this study?

Accepted Answer

It helps ensure that differences in yield are due to the fertilizer and not to pre-existing differences between plots.

Answer

It guarantees that all plots produce the same yield before the study.

Answer

It allows the researchers to generalize results to all types of crops.

Answer

It eliminates all measurement error in yield calculations.

Question 5

An observational study of 2,000 adults finds that people who meditate daily have lower rates of anxiety. A therapist concludes that meditation eliminates anxiety. Which limitation is most important to acknowledge?

Accepted Answer

Self-selection bias: people who choose to meditate may already have lower baseline anxiety.

Answer

The sample size is too small to draw conclusions.

Answer

The study should have included a placebo group.

Answer

Meditation is not a measurable variable.

Question 6

A school randomly assigns 30 classrooms to use standing desks and 30 to use traditional desks for one academic year. At year-end, students with standing desks show better focus scores. What design feature allows the strongest causal conclusion?

Accepted Answer

Random assignment of classrooms to conditions

Answer

The large number of classrooms studied

Answer

Measuring focus scores at the end of the year

Answer

Comparing two types of desks rather than one

Question 7

An observational study follows 10,000 adults for 15 years and finds that those who consume more whole grains have lower rates of diabetes. Which of the following would most strengthen the argument that whole grain consumption prevents diabetes?

Accepted Answer

A randomized controlled experiment in which participants are randomly assigned to eat more whole grains or a control diet and followed for the same period

Answer

A larger observational study with 100,000 participants

Answer

An observational study conducted in a different country

Answer

A survey of participants about their grain preferences