COMPARISON OF HEIGHT ACCELERATION CURVES IN THE FELS, ZURICH, AND BERKELEY GROWTH DATA

A new type of smoothing spline designed for nonparametric estimation o f growth acceleration curves was applied to longitudinal measures of h eight from the Fels, Zurich, and Berkeley growth studies. Landmark fea tures of the individual acceleration curves were located and examined for site effects and site by sex interaction. The curves in each group were structurally averaged by transforming the age scale of each chil d to align the landmarks with overall means. The modal shapes of the s tructural average curves were found to be highly similar in the three studies, although the relative number of children who conformed to the modal pattern differed among the studies. Significant site by sex int eractions were found in the timing of the landmarks associated with th e pubertal growth spurt and with the prepubertal 'midspurt'.