A Study on the Normality of Distribution of the Physique Data in the Japanese Youth

Abstract

To examine whether or not the frequeucy polygons of the chest circumference data in 291, 736 Japanese youth from 6 to 21 years old in 1971 were the normal curves, the tests of normality with reference to k-sta-tistics were carried out on the frequency distributions of the chest circumference data. At the additional interest, the skewness and kurtosis observed in the distributions of the chest circumference were compared against those reported for the standing height, the sitting height, and the body weight.
The following results were obtained.
1) The skewness coefficients for the chest circumference data in the Japanese youth were significantly positive with the exception of 14 year-old boys who had symmetric distribution.
2) The maximum and the minimum positive skewness in the distributions of the chest circumference appeared at the ages of 11 and 14 years for the boys, and 11 and 13 years for the girls.
3) Only fourteen and sixteen year-old girls had the mesokurtic frequency distributions in the measure of kurtosis. The significant platykurtosis appeared at the ages from 13 through 17 years in the boys, and from 11 through 13 and 17 years in the girls. Most of the other age groups in both sexes had the significant leptokurtosis.
4) The maximum positive skewness of the boys and the girls appeared at the ages of 11.5, 9 years in the standing height, 11.5, 10 years in the sitting height, 8, 7 or years in the body weight and 10, 10 years in the chest circumference. The maximum negative skewness of the boys and the girls appeared at the ages of 14, 12 years in the standing heiget and 14, 13 in the sitting height. The minimum positive skewness of the boys and the girls appeared at the ages of 14 and 13 years in both the body weight and the chest circumference.
5) The maximum platykurtosis (leptokurtosis) of the boys and the girls appeared at the ages of 13(15), 11(14) years in the standing height, 13(19), 11(21) years in the sitting height, 13(7), 12(7) years in the body weight and 14(7), 17(20) years in the chest circum-ference.