Research that collects data simultaneously from people of different ages, in contrast to a longitudinal study, which follows one group of subjects over a period of time.
A cross-sectional study is a research method where data are collected at the same time from people in different age categories. It contrasts with the method, known as longitudinal study, where the same group of subjects is studied over time. One weakness, or confounding variable, of the cross-sectional study is that its subjects, in addition to being different ages, are also born in different years, and their behavior may thus be influenced by differences in education, cultural influences, and medical treatment. In the longitudinal study, data can be obtained from subjects of different ages born within the same period of time. However, a confounding variable in longitudinal studies is the degree to which each person's environmental influences will vary from those of others over the period of time covered by the experiment.