Longitudinal studies utilize a research design that measures the same variables of interest repeatedly over a period of time for the same group of participants. This design allows researchers to examine change within individuals and contextual factors that account for interindividual differences. The analysis of data from such designs is common in educational, psychological, and sociological research. Examples of studies that made use of longitudinal data analysis are research on problem behavior and psychosocial development in youth published by Richard Jessor and Shirley Jessor in 1977, Michael Resnick and colleagues’ 1997 analysis of data from the National Longitudinal Study of Adolescent Health, and a 2012 study of the impact of a positive youth development program on the development of adolescents’ risk behavior by Daniel Shek ...