Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 4

Question 1

A biology teacher randomly selects 30 students from her class to test a new lab activity, then compares their quiz scores to the remaining students.
She finds the selected students score higher.
Can she conclude the new lab activity causes higher quiz scores?

Accepted Answer

No, because random selection for one group does not constitute random assignment to treatment and control groups.

Answer

Yes, because she randomly selected the group.

Answer

Yes, because the sample is representative of her class.

Answer

No, because quiz scores are too variable to analyze.

Question 2

Researchers randomly assign 100 trees in an orchard to receive a new fertilizer and 100 trees to receive standard fertilizer. The treated trees yield 20% more fruit. What is the most appropriate conclusion?

Accepted Answer

The new fertilizer likely causes higher fruit yield in orchards similar to the one studied.

Answer

The new fertilizer causes more fruit yield in all fruit trees worldwide.

Answer

There is a correlation between fertilizer type and fruit yield, but no causal link.

Answer

The 20% increase is too small to be meaningful.

Question 3

A university study randomly assigns incoming students to two groups: one receives a financial literacy workshop and one does not. After one year, the workshop group has higher savings rates. Which conclusion is most appropriate?

Accepted Answer

Among students similar to those in this university, attending the workshop likely causes higher savings.

Answer

The financial literacy workshop causes higher savings rates for all college students.

Answer

The students who didn't attend the workshop were irresponsible with money.

Answer

The correlation between workshops and savings is not statistically meaningful.

Question 4

A study surveys adults about coffee consumption and heart disease risk, finding that higher coffee drinkers have lower heart disease rates. A cardiologist concludes that drinking coffee prevents heart disease. Which of the following is the most important criticism?

Accepted Answer

This is an observational study; the relationship could be explained by confounding variables.

Answer

The study should have measured caffeine levels, not coffee cups.

Answer

The study sample was too small to draw conclusions about heart disease.

Answer

Heart disease rates cannot be measured in survey-based studies.

Question 5

A researcher conducts a randomized controlled trial with 400 participants drawn from a single urban hospital. The treatment is found to be effective. A policy maker wants to apply the findings to rural populations. What is the main concern?

Accepted Answer

The study sample from an urban hospital may not represent rural populations, limiting generalizability.

Answer

Randomized trials cannot establish effectiveness.

Answer

Rural populations are too small to be studied separately.

Answer

Random assignment is only valid when samples are from multiple locations.

Question 6

An observational study finds that students who eat breakfast score higher on standardized tests. Which of the following, if true, would most weaken the claim that breakfast causes higher test scores?

Accepted Answer

Students from higher-income families are more likely to eat breakfast and also have greater access to test-prep resources.

Answer

The study included both rural and urban students.

Answer

The test score difference was statistically significant.

Answer

The study was conducted over three consecutive years.

Question 7

Which of the following study designs allows researchers to conclude that Treatment X causes Outcome Y?

Accepted Answer

A randomized controlled experiment in which participants are randomly assigned to receive X or a placebo

Answer

An observational study with a large, nationally representative random sample

Answer

A longitudinal survey tracking participants over 10 years

Answer

A cross-sectional study comparing groups at a single point in time