Figure 1

Height vs. age data from dataset 1, British boys (1965): empty circles. The solid curves represent the fitting of the data by means of the classes (a) U1, (b) (U 1 + F 1), respectively. The (U 1 + G 1) fitting curve is visually indistinguishable from (U 1 + F 1), and therefore is not shown separately. The fitting parameters and R² values are reported in Table 2.