Question 23·Medium·Evaluate Statistical Claims: Observational Studies and Experiments
Researchers selected at random 150 public high schools in Texas and recorded the percentage of students at each school who participate in after-school tutoring programs.
To which population is it most appropriate to generalize the results of this study?
For questions about which population you can generalize to, first underline the exact description of the sample (who was chosen and from where). Then list the key traits of that sample—such as public vs. private, grade level, and location. Quickly scan each answer choice and eliminate any that (1) add people who weren’t sampled (like private or younger students) or (2) expand the region beyond where the sample came from. The remaining choice that matches all the sample’s traits is your answer.
Hints
Focus on the description of the sample
Underline or note the key words in the first sentence: what type of schools were chosen, and where are they located?
Think about who is not included
Ask yourself: Are private schools included? Are middle and elementary schools included? Are schools from other states included? That tells you who the data can and cannot represent.
Compare each choice to the sample
For each answer choice, check whether it adds groups that were never studied (like different grade levels, private schools, or other states). Eliminate any choice that goes beyond the kind of schools described in the prompt.
Step-by-step Explanation
Identify who was actually studied
The study says researchers selected at random 150 public high schools in Texas and recorded the percentage of students at each school who participate in after-school tutoring.
So the data come from:
- public schools (not private),
- high schools (not middle or elementary),
- located in Texas (not other states).
Recall what population you can generalize to
In statistics, you can generalize study results to a population that matches the group you sampled on all important characteristics.
Here, the important characteristics are:
- public vs. private,
- high school vs. other grade levels,
- location (Texas vs. other states).
The population should include all individuals like those in the sample, not people with different types of schools or from different regions.
Match answer choices to the sample characteristics
Look at each answer choice and ask three questions:
- Does it limit to public schools only (not all schools)?
- Does it limit to high school students only (not all students in all grades)?
- Does it limit to Texas only (not the entire United States)?
Eliminate any choice that fails any of these three tests.
Choose the population that matches on all characteristics
The only answer choice that is limited to public, high school, and Texas is “All public high school students in Texas,” which corresponds to choice C.