A claim about a broad population needs a representative sample, a group selected without systematically leaving parts of that population out. Compare the people named in the conclusion with who could enter the study, then check how participants were chosen. A large number of responses from one convenient location can still give a misleading picture of the wider group.
Hints
- Hint 1
“Most adults” names the target population, the full group the nutritionist wants to describe. Compare that group with the people who took part. Were adults outside the gym included?
- Hint 2
A convenience sample draws from people who are available rather than selecting people at random from the whole population. Could gym members’ exercise habits or energy levels differ from those of other adults?
Step-by-step
Compare the sample with the claim
Step 1Identify who the conclusion describes
No Desmos needed. A calculator can't tell you whom a study represents. The conclusion says “most adults,” so the target population, the full group the claim describes, is adults generally.
- Step 2
Check who was recruited
The nutritionist recruited members of her local gym, not adults randomly selected from the whole population. Gym members may have different exercise habits or energy levels from other adults, so their responses may not represent adults generally.
- Step 3
Match the flaw to the conclusion
The 68 reports of feeling more energetic describe the participants, not the whole adult population. To generalize, or extend a result to a wider group, the sample must represent that group. Recruiting from one gym rather than randomly selecting adults is the listed flaw that most directly weakens the conclusion about most adults. Choice C.