XXVIII. The evaluation of anthropometric data. 



A large proportion of the problems that the medical 

 man has to solve involves the finding of averages of a 

 large number of observations. This is sure to be true of 

 all anthropometric problems. In the course of the pre- 

 ceding lesson valuable anthropometric data were collected 

 and recorded upon cards. The value of this material is 

 purely potential. Before the data will furnish a basis for 

 drawing conclusions it is necessary to subject it to a pro- 

 cess of evaluation. This process consists, first, in group- 

 ing; second, in getting the average or the median value 

 for each measurement; and, third, in graphically repre- 

 senting the averages. In the previous lesson the observer 

 noted upon each card whether the subject had lived in a 

 hilly or in a flat country; further, whether he had led a 

 physically active or inactive life. This gives one an op- 

 portunity for four groups when the cards from the whole 

 class are collected. 



Group I. Active men from a hilly country. 

 " II. " " " flat " 



" III. Inactive " " hilly " 

 " IV. " " " flat " 



Until recently it has been customary to simply write 

 the data for any group in columns and "strike an average" 

 of each column. If there are only 10 to 20 or 30 individ- 

 uals in each group this method does not entail the unnec- 

 essary expenditure of much energy, but it is not reliable; 

 for one " giant " or " dwarf " in any group would vitiate 



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