Analysis of the velocity curve for height by the wavelet interpolation method in children classified by maturity rate.

The Wavelet Interpolation Method (WIM) developed by Meyer ([1992] Wavelets and Operators. Cambridge: Cambridge University Press) has been proposed as an analytical method for the accurate description of longitudinal growth velocity in height and identification of the age at maximum peak velocity (MPV) in the curve. The distance curve in height was determined by interpolating the longitudinal records of 98 boys and 88 girls, 6-17 years old, with the WIM. The distance curve was then differentiated to obtain a velocity curve. Age at MPV estimated from the velocity curve was utilized as a criterion of maturity rate (timing), and five maturity groups (early, little early, average, little late and late) were defined in both sexes. Four type models were derived from the occurrence of secondary peaks (mid-growth spurt and after-growth spurt): type model A, appearance of a mid-growth spurt and MPV; type model B, appearance of an after-growth spurt and MPV; type model C, appearance of a mid-growth spurt, an after-growth spurt and MPV; and type model D, appearance of MPV only. The individual growth data of boys and girls classified by maturity rate were sorted into the four type models. The frequency of occurrence of the four type models in groups classified by maturity rate was then analyzed, and the characteristics of height growth velocity was examined in boys and girls. Am. J. Hum. Biol. 11:13-30, 1999. Copyright 1999 Wiley-Liss, Inc.