Question 17·Medium·Evaluate Statistical Claims: Observational Studies and Experiments
A researcher wanted to investigate whether listening to classical music while studying improves concentration. Sixty volunteer college students were randomly assigned to two groups of 30 students each. One group listened to classical music while studying for two hours, and the other group wore noise-canceling headphones with no music. Immediately afterward, all students took the same concentration test. The music group earned an average score of 78, whereas the silent group earned an average score of 70.
Based on the results of this experiment, which of the following statements is supported?
I. Listening to classical music causes college students to score exactly 8 points higher on this concentration test than students who study in silence.
II. The experiment provides evidence that listening to classical music can improve concentration for college students similar to those who participated in the study.
For SAT questions about interpreting studies, first identify whether the study is an observational study or a randomized experiment. Randomized experiments justify causal language (the treatment causes changes in the outcome), but conclusions should still be cautious: talk about “evidence” and “can improve” rather than guarantees or exact effects. Always read each statement’s wording very carefully—watch for overclaims like “exactly,” “all,” or sweeping generalizations beyond the sample—and accept only those conclusions that match what the design and data reasonably support for people similar to the participants.
Hints
Think about the study design
Ask yourself: were students just observed in their usual environments, or were they randomly assigned to conditions (music vs silence)? How does random assignment affect whether we can talk about cause and effect?
Focus on the wording of statement I
Pay close attention to the words “causes” and “exactly 8 points higher.” Does the experiment show that every similar student will always gain exactly 8 points, or does it just show what happened, on average, in this particular sample?
Focus on the wording of statement II
Look carefully at the phrases “provides evidence,” “can improve,” and “similar to those who participated.” Are these claims too strong, or are they cautious enough to match what one randomized experiment can reasonably show?
Compare the strength of the two claims
Which statement is making a stronger, more absolute claim, and which one is making a more cautious, evidence-based claim? The SAT usually expects you to accept careful, modest conclusions and reject ones that go beyond what the data can support.
Desmos Guide
Confirm the observed difference in means
In Desmos, type 78 - 70 to confirm that the sample’s music group mean score is 8 points higher than the silent group’s mean. Then reflect on whether seeing an 8-point difference in one sample is enough to claim that all college students will always improve by exactly 8 points, or whether it simply suggests an improvement for similar students on average.
Step-by-step Explanation
Identify the type of study and what it allows you to conclude
The researcher randomly assigned the 60 volunteer students into two groups: one with classical music and one with silence. Because of random assignment, this is a controlled experiment, not just an observational study. Controlled experiments with random assignment allow us to make causal conclusions about the effect of the treatment (listening to classical music) on the outcome (concentration test scores), at least for people similar to those in the study.
Examine what statement I is really claiming
Statement I says: Listening to classical music causes college students to score exactly 8 points higher on this concentration test than students who study in silence.
Key issues:
- The experiment found that this sample’s music group had an average of 78 and the silent group had an average of 70, so the observed difference in this group was 8 points.
- However, in other random samples of similar students, the difference will naturally vary because of chance; it will not always come out to be exactly 8.
- Also, this statement sounds like it applies to all college students, not just ones similar to those who volunteered.
So this wording is too strong and too precise: we have evidence of an improvement, but not proof that the true effect for all college students is exactly 8 points every time.
Examine what statement II is really claiming
Statement II says: The experiment provides evidence that listening to classical music can improve concentration for college students similar to those who participated in the study.
This wording is much more careful:
- “Provides evidence” matches what a single experiment can do; it does not claim absolute proof.
- “Can improve” allows for the idea that scores may improve on average, not that every individual will always improve by a fixed amount.
- “Students similar to those who participated” respects that the subjects were volunteer college students; the result is most trustworthy for a similar population, not for everyone everywhere.
This matches what conclusions are appropriate from a randomized experiment with volunteer college students.
Decide which statements are supported
From the reasoning above:
- Statement I goes beyond the data by claiming an exact 8-point causal effect for college students in general, which the experiment does not justify.
- Statement II makes a cautious, appropriate claim about evidence for improvement in students similar to those in the experiment.
Therefore, only statement II is supported, so the correct choice is II only.