1923- ^*'o. 4- PHYSICAL DEVELOPMENT OF CHILDREN AND YOUNG PEOPLE. 7 



the arithmetical average, ± the probable error. F. inst. : 9 }cars old boys 

 (higher schools) average 134.14, probable error 0.57. The perpendicular 

 line marks this deviation. Similar computation and its corresponding 

 marking on millimeter paper has been done for all ages, after which the 

 most natural and even course of tlie curves has been drawn within the 

 borders of these lines, regardless whether the curve hits the arithmetical 

 average or some other point within the borders of the probable error. 

 The "rounded off values" — cfr. the tables — are read off after the 

 curves. This mode of proceeding I regard as the most correct, the one 



nM^>n. 



7;vV 



9 ja 11 te 15 N 15 j(5 n is ie îdjcai-s 



Fig. r a. Higher schools. 



which best reflects the real phenomena in question ®. The probable error 

 for the public school material is so minimal, that it does not make any 

 difference. 



Herewith we shall proceed to the study of the curves: — Fig. i b. 

 As regards the public school children, the boys are the tallest until about 

 exactly ii.o years. Then they are overtaken by the girls, who then are 

 the tallest as far as our material reaches, that is to 14.0 years. Judging 

 from tlie course of tlie curve and probable continuation the precedence 



" Cf. f. inst, the course of the curve between 17 and 20 years for high school boys. 

 A line between the arithmetical average numbers would have given a false con- 

 ception of the course. The method used gives no doubt a much more correct pre- 

 sentation of the laws of physical development. Only to present the average 

 numbers — as is often done — without considering probable errors, frequentlv 

 leads to altogether wrong conclusions and conceptions. 



