What is a major drawback of cross-sectional designs?

What is a major drawback of cross-sectional designs?

• A. They do not allow for the study of individual development trends and may distort age differences.
• B. They allow for investigation of developmental trajectories.
• C. They guarantee identical results across cohorts.
• D. They are immune to practice effects.

Answer: (A)

Cross-sectional designs compare different people at one moment in time, which lets us spot age differences but not how a given individual changes as they grow. The major drawback is that these age differences can be muddled by cohort effects—the idea that differences between age groups may reflect the distinct experiences of each generation rather than true developmental change. For example, differences in cognitive performance across age groups might stem from differences in schooling, nutrition, or culture that exist between generations, not from aging itself. This is why longitudinal designs, which follow the same individuals over time, are better for mapping developmental trajectories, even though they come with their own challenges like practice effects and participant attrition. The other choices don’t fit because cross-sectional designs do not reveal developmental trajectories, they do not guarantee identical results across cohorts, and while they reduce practice effects compared to repeated testing in a single group, they are not described as immune to them.

Cross-sectional designs compare different people at one moment in time, which lets us spot age differences but not how a given individual changes as they grow. The major drawback is that these age differences can be muddled by cohort effects—the idea that differences between age groups may reflect the distinct experiences of each generation rather than true developmental change. For example, differences in cognitive performance across age groups might stem from differences in schooling, nutrition, or culture that exist between generations, not from aging itself.

This is why longitudinal designs, which follow the same individuals over time, are better for mapping developmental trajectories, even though they come with their own challenges like practice effects and participant attrition.

The other choices don’t fit because cross-sectional designs do not reveal developmental trajectories, they do not guarantee identical results across cohorts, and while they reduce practice effects compared to repeated testing in a single group, they are not described as immune to them.