Читать книгу Lifespan Development - Tara L. Kuther - Страница 90

A cross-sectional research study compares groups of people of different ages at a single point in time. For example, to examine how alcohol use changes from 6th through 12th grade, a scientist might visit a school system in 2020 and administer a survey about alcohol use to students ages 12, 14, 16, and 18. By analyzing the survey, the scientist can describe age differences in alcohol use and identify how 12-year-olds differ from 18-year-olds. However, the results do not tell us whether the observed age differences in alcohol use reflect age-related or developmental change. In other words, we don’t know whether the 12-year-olds will show the same patterns of alcohol use as the current 18-year-olds when they are 18, six years from now.

Cross-sectional research permits age comparisons, but participants differ not only in age but also in cohort, limiting the conclusions researchers can draw about development. Recall that a cohort is a group of people of the same age who are exposed to similar historical events and cultural and societal influences. The 12-year-olds and the 18-year-olds are different ages, but they are also in different cohorts, so the two groups may differ in reported alcohol use because of development (age-related changes) or cohort (group-related changes). For example, perhaps the 12-year-olds received a new early prevention program at school that was not available to the 18-year-olds when they were 12. The difference in alcohol use between 12-year-olds and 18-year-olds might then be related to the prevention program, not to age. Cross-sectional research is an important source of information about age differences, but it cannot provide information about age change.