Estimation of maximum increment age in height and weight during adolescence and the effect of World War II

An attempt was made to estimate the maximum increment age (MIA) in height a nd weight of Japanese boys and girls during the birth years 1893-1990 throu gh the published data of the Ministry of Education, Science, Sports and Cul ture in Japan. In cases where the same maximum annual increment occurred in two or three successive age classes in a birth year cohort, a new formula (see Eq. 2) was developed to estimate the MIA. The existing formula for est imating MIA was modified to remove the mathematical deficiency (Eq. 1). Est imated MIA shows an overall declining trend, except in birth year cohorts 1 934-1951. The effect of World War II on MIA was investigated by a dummy var iable regression model. On average, during the birth years 1934-1951, MIA i n height decelerated by 1.35 years in boys and 0.54 year in girls, while MI A in weight decelerated by 0.95 year in boys and 0.78 year-in girls. (C) 20 00 Wiley-Liss, Inc.