Question 2·Medium·Evaluate Statistical Claims: Observational Studies and Experiments
A researcher posted an online questionnaire on a school district's website asking all high-school students to report their average daily time on social media and their most recent math exam score. A total of 350 students voluntarily completed the questionnaire. The researcher found that students who reported more than 3 hours per day on social media had, on average, lower math exam scores than those who reported less than 1 hour per day.
Which statement best describes the conclusion that can be drawn from this study?
For SAT questions about conclusions from studies, always check two things quickly: (1) Was there random assignment to treatments? If yes, you may be able to claim causation; if not, you are limited to association. (2) Was there random sampling from a clearly defined population? If yes, you can generalize to that population; if not, restrict your conclusion to the actual group studied. Then pick the answer that matches both the correct strength of claim (association vs. causation) and the correct population (sample vs. larger group).
Hints
Think about how the data were collected
Ask yourself: Did the researcher assign students to different amounts of social media use, or did students simply report what they already do?
Causation vs. association
Look at which answer choices use the word "causes" versus words that only describe a relationship. Given the type of study, what kind of claim is too strong?
Who can we talk about?
Consider who actually provided data: Were they randomly selected from all high-school students nationwide, or did a specific group choose to respond?
Match wording to limitations
Use your answers to: (1) whether causation is justified and (2) how broad the population is, then eliminate choices that go beyond those limits.
Step-by-step Explanation
Identify the type of study
Read how the data were collected: students voluntarily completed an online questionnaire about their social media use and math scores. No one was assigned to use more or less social media. That means this is an observational study with voluntary response, not an experiment.
Decide if causation can be claimed
Causation (saying that one thing causes another) can usually be concluded only from a well-designed experiment with random assignment to treatments. Here, students already had their own social media habits; the researcher just recorded them. Because there is no random assignment, we cannot say that social media use causes changes in math scores—only that they are related.
Decide who the results can be generalized to
Next, look at who was studied and how they were chosen. The questionnaire was posted on a single school district's website, and 350 students voluntarily responded. There is no mention of a random sample from the district, and definitely not from all high-school students nationwide. Therefore, we cannot generalize the results to all high-school students. We are safe only describing the group that actually responded to the questionnaire.
Match the correct wording to the study limits
Now compare the answer choices:
- Eliminate any choice that says "causes" (because there was no experiment).
- Eliminate any choice that makes a claim about "all high-school students nationwide" (because there was no random national sample).
The only remaining choice should state a non-causal relationship (an association) and limit the claim to the students who responded to the questionnaire.
State the conclusion clearly
So, based on this observational, voluntary-response survey, the strongest justified conclusion is that among the 350 students who responded, higher reported social media use is associated with lower math exam scores on average.
Correct answer: There is an association between social media use and math exam scores among the students who responded to the questionnaire.