Which statement is a limitation of cross-sectional designs?

• A. Time-consuming data collection
• B. Attrition of participants over time
• C. Cohort effects can confound age comparisons
• D. High cost of long-term follow-up

Answer: (C)

Cross-sectional designs compare different age groups at one point in time, so they can’t easily separate aging effects from cohort effects. Cohort effects come from people born in different years experiencing unique historical, social, and educational environments. Those generational experiences can produce differences that look like changes due to getting older but are actually due to being from a different birth cohort. For instance, variations in vocabulary, technology use, or attitudes might reflect schooling or cultural context specific to a generation rather than true age-related development. This makes it hard to tell whether observed differences are about aging or about the distinct experiences of each cohort.

In contrast, following the same individuals over time (a longitudinal approach) helps disentangle aging from cohort influences by tracking changes within the same people as they age, even though longitudinal studies come with other challenges like attrition and higher costs.