COMBINED EFFECTS OF THE TEMPO OF MATURATION AND MID-PARENT HEIGHT ON THE SHAPE OF INDIVIDUAL GROWTH-CURVES

The concurrent effects of mid-parent height and tempo of maturation on variation of the individual growth curve were examined. Data of 183 b oys from the Wroclaw Growth Study were used. The functional and biolog ical parameters were derived from fitting Preece-Baines model 1 to ind ividual data. All subjects were divided into three categories of mid-p arent height and maturation rate, resulting in nine groups. MANOVA sho wed significant differences in the functional and biological parameter s for three maturity and mid-parent height groups, separately. However , insignificant interactions indicated independence of the two factors . Univariate analysis revealed that the first factor (tempo of maturat ion) adjusts time and velocity at the beginning (T1, V1) and peak (T2, V2) of the adolescent growth spurt. This factor accounts for the shap e of the curve. It places the curve along age and velocity axes. The o ther factor (mid-parent height) is responsible for general elevation o f the growth curve on the centile distribution, placing it on the appr opriate centile. This regulates height parameters, i.e., height at tak eoff (H1), height at peak height velocity (H2), and adult height (AH). The simultaneous influence of the two factors leads to estimation of a more specific and more probable type of a curve. This kind of the es timation allows diminishing variance and prediction error. (C) 1997 Wi ley-Liss, Inc.