What are the social, economic, and biological factors during adolescence and young adulthood that lead to chronic disease and poor health outcomes later in life? This is the kind of question that can only be answered by a longitudinal study—that is, a study that tracks a representative cohort of individuals over years, or even decades, assessing their health status at periodic intervals and drawing carefully weighted conclusions from the results. Read The National Longitudinal Study of Adolescent to Adult Health
