One advantage to using a longitudinal design over a cross-sectional design is that longitudinal designs:

A) are typically cheaper to perform.
B) are less likely to be affected by attrition.
C) avoid the problems associated with cohort effects.
D) require less time to perform.

Answer: C
Rationale: Studying one group for a longitudinal study can cost a lot of money and time. This research design is also hampered by the issue of attrition. Despite these drawbacks, one clear advantage to using a longitudinal design over a cross-sectional design is that cross-sectional designs can be complicated by cohort effects, which are not an issue for longitudinal designs.