Existing data on the body measurement, which did not adopt the sampling method, are often unavailing. And so the author measured the foot of the students (5-18 years old) in Tokyo, using stratified three-stage sampling. As the coefficient of variation of foot-length is within 6%, size of about 35 subjects at each age (population of universe is 45, 500) is sufficient to estimate population at accuracy 1%. The results obtained are as follows;
(1) Mean value, unbiased variance and coefficient of variance of stature, height of Spina ilica ventralis, smallest girth of the lower leg, foot-length, foot-breadth, instep-height, heel-breadth, foot-girth measured at the same position as footbreadth, and foot-girth in the instep-height are shown on table 1 at each age.
(2) Differences between the mean values of the adjoining ages were tested as shown on table 2.
(3) We might conclude that foot-length grows up to 16 years old (male) and 14 (female); and foot-breadth 17 (male) and 17 (female); instep-height 13 (male) and 14 (female); and foot-girth 18 (male) and 17 (female). The foot-growth ends in the order of height, breadth and length. Stature increases up to 18 (male) and 17 (female) which ages are the latest in this data.
(4) Sexual differences as to foot-length and foot-breadth are not observed in 7-12 age.
(5) Growth of foot at about 6 years of age is notable. Female students begin to grow rapidly about one year earlier than male.
(6) We might conclude that the large value of unbiased variance means rapid growth. In this sense, growth at the age of 11 (male) is significant.
(7) Growth of foot stops sooner than stature. We believe this relative swiftness of foot growth is connected with the fact that man walks at erect posture.
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