In longitudinal studies, the threat where age-related changes could account for observed differences is known as?

• A. Maturation
• B. History effects
• C. Attrition
• D. Instrumentation

Answer: (A)

Maturation is the threat in longitudinal designs where age-related development could explain observed changes over time. As participants naturally grow or develop, their abilities, behaviors, or symptoms can change independent of any intervention or measurement timing, making it hard to tell whether observed differences are due to the variable of interest or simply aging. For example, improvements in cognitive performance over several years might reflect developmental progress rather than the effect of a treatment. History effects involve external events affecting participants at a particular time, attrition refers to dropout that can bias results, and instrumentation means changes in measurement methods or raters over time.