Читать книгу Infants and Children in Context - Tara L. Kuther - Страница 77

A longitudinal research study follows the same group of participants over many points in time. Returning to the previous example, to examine how vocabulary changes between Grades 1 and 7, a developmental scientist using longitudinal research would measure children’s vocabulary size in first grade, then follow up 2 years later in third grade, then 2 years later in fifth grade, and finally 2 years later in seventh grade. This longitudinal study would take 6 years to complete.

Longitudinal research provides information about age change because it follows people over time, enabling scientists to describe how the first graders’ vocabulary progressed through childhood. However, longitudinal research studies only one cohort or age-group over time. Are the findings due to developmental change or are they specific to the children studied? Is the pattern of change experienced by these children over a 6-year span similar to other cohorts or groups of children? Because only one cohort is assessed, it is not possible to determine whether the observed changes are age related or unique to the cohort examined.