Bluebook SAT Test Evaluating Statistical Claims: Observational Studies and Experiments 3

Question 1

A researcher randomly selects 1,000 adults from across the United States and finds that adults who sleep 8 hours per night report higher life satisfaction.
Which statement is best supported by this study?

Accepted Answer

There is an association between sleeping 8 hours and higher life satisfaction that is likely representative of U.S. adults.

Answer

Sleeping 8 hours per night causes higher life satisfaction in U.S. adults.

Answer

All U.S. adults should sleep exactly 8 hours per night.

Answer

The study proves that sleep quality is more important than sleep quantity.

Question 2

A study randomly assigns participants to two diet groups for 12 weeks: a high-protein diet or a standard diet. The high-protein group loses significantly more weight. Which conclusion is best supported?

Accepted Answer

A high-protein diet causes more weight loss among people similar to study participants.

Answer

All people who try a high-protein diet will lose more weight.

Answer

There is only a correlation between diet and weight loss, not a causal link.

Answer

The standard diet group's results are invalid because they served as a control.

Question 3

An observational study follows 5,000 people over 20 years and finds that those who regularly volunteer have longer lifespans. What is the most important limitation of this finding?

Accepted Answer

Since participants were not randomly assigned to volunteer or not, the association could be due to confounding variables such as overall health or social status.

Answer

The study followed too few people to be meaningful.

Answer

Volunteering cannot be measured objectively.

Answer

The 20-year period is too short to assess lifespan effects.

Question 4

A school randomly selects 80 students to participate in a new after-school reading program and observes that they read better at year-end than a comparison group. Which aspect of the study design limits the strength of a causal conclusion?

Accepted Answer

The students were randomly selected but not randomly assigned to treatment and control groups.

Answer

The sample of 80 students is too small for any conclusion.

Answer

Reading improvement cannot be measured accurately in schools.

Answer

The study should have been conducted over multiple years.

Question 5

A poll randomly samples 2,000 U.S. adults and finds that 65% support stricter environmental regulations. Based on this, which conclusion is valid?

Accepted Answer

Approximately 65% of U.S. adults support stricter environmental regulations.

Answer

Stricter environmental regulations will pass in the next election.

Answer

Every U.S. adult either supports or opposes stricter regulations with equal probability.

Answer

The result proves that environmental concerns cause political preferences.

Question 6

A study randomly assigns 300 volunteers to meditate for 20 minutes daily or to sit quietly for 20 minutes daily and then measures their stress levels. Which of the following questions can the study best answer?

Accepted Answer

Does meditation lower stress compared to quiet sitting for people like those in the study?

Answer

Does meditation lower stress for all people worldwide?

Answer

Is there a correlation between meditation habits and personality type?

Answer

Would stress levels have changed even without the intervention?

Question 7

In a study of exercise and mood, participants self-selected into either an exercise group or a sedentary group. Those who exercised reported better moods. Which design change would most improve the ability to conclude that exercise causes better mood?

Accepted Answer

Randomly assigning participants to the exercise or sedentary group

Answer

Increasing the sample size

Answer

Surveying participants about their mood before the study

Answer

Conducting the study over a longer time period