Age and gender effects in 10 physical self-concept scales for elite athletes and nonathletes were based on responses from 4 age cohorts (grades 7-10 in high school) who completed the same instrument 4 times during a 2-year period. A multicohort-multioccasion design provides a stronger basis for assessing development differences than a cross-sectional comparison collected on a single occasion or a longitudinal comparison based on responses by a single age cohort collected on multiple occasions. Across all 10 physical self-concepts there were substantial differences due to group (athletes greater than nonathletes), gender (males greater than females), and gender x group interactions (athletes less than nonathletes in gender differences). There were no significant effects of age cohort and only very small effects of occasions. Thus longitudinal and cross-sectional comparisons both showed that mean levels of physical self-concept were stable over this potentially volatile adolescent period and that this stability generalized over gender, age, and athlete groups.
Herbert W. Marsh is with the Faculty of Education at the University of Western Sydney, New South Wales, Australia.