Question: What is a problem with using cross-sectional research designs in developmental science? Need Assignment Help? Multiple Choice Question It is not possible to find differences in variables by age in a cross-sectional design. Cross-sectional design makes it difficult to follow the same people across multiple time points. It is limited to observing small groups of individuals, but larger groups of people might have different experiences. Findings might relate to developmental changes but could also relate to differences in cohort.