Longitudinal studies following the same individuals over decades provide insights observational snapshots cannot. However, these studies face attrition—participants move, lose interest, or die. Those who remain in studies for thirty years may differ systematically from those who drop out (typically those with more chaotic lives). Thus, conclusions about aging may inadvertently describe successful agers who could be tracked, not the aging population generally.
It can be inferred from the text that
research findings may be shaped by which subjects are systematically included or excluded
longitudinal studies are less valuable than observational snapshots
attrition affects all participants equally
people with chaotic lives never age
Correct Answer: A
Choice A is the best answer. Attrition systematically excludes certain types of people.
- Context clues: Drop-outs differ systematically; conclusions may describe only "successful agers."
- Meaning: Who remains in a study shapes what conclusions can be drawn.
- Verify: The warning that findings may not represent the general population shows selection effects.
đź’ˇ Strategy: When systematic differences exist between included and excluded subjects, infer selection bias.
Choice B is incorrect because longitudinal studies "provide insights" despite this limitation. Choice C is incorrect because attrition affects those with "more chaotic lives" differently. Choice D is incorrect because they age but aren't tracked.