Jo. Ramsay et al., COMPARISON OF HEIGHT ACCELERATION CURVES IN THE FELS, ZURICH, AND BERKELEY GROWTH DATA, Annals of human biology, 22(5), 1995, pp. 413-426
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'.