Cross-Sectional Study refers to a a study in which separate groups of subjects at different ages are compared. For example, a study in which the intelligence of a group of ten-year-olds on a language comprehension test is compared to the performance of a difference group of eleven-year-olds.

Moreover, Cross-sectional study refers to a research design in which the behavior of individuals of different ages, social backgrounds, or environmental settings is measured once to acquire information about the effects of these differences; a study in which developmental differences are identified by testing people of different ages