178 A BIOMETRIC STUDY OF BASAL METABOLISM IN MAN. 



predicted the heat-production from constants based on other series 

 of individuals taken as the bases of standard constants. The compari- 

 son of heat-productions thus calculated with those which have been 

 actually determined furnishes a test of the accuracy of prediction by 

 the several methods to be tested. 



From the theoretical side it is evident that in testing the value of 

 any method of predicting metabolism, the measurement of an indi- 

 vidual subject should not be included in the series upon which the 

 constant or equation used in predicting his own metabolism is based. 

 In other words, the metabolism of an individual should not be predicted 

 from itself. This error has in essence been made by earlier writers in 

 tests of the validity of the body-surface law. 



But while a single aberrant subject might have great weight in 

 determining a standard constant based on a small group of individuals, 

 the importance of any single metabolism measurement rapidly de- 

 creases as the number included in the group becomes larger. Thus 

 in our series of males one individual has a weight of only 1/136 and in 

 our series of females one individual has a weight of only 1/103 in 

 determining the constant for the whole series. In predicting the 

 metabolism of really, and not merely supposedly, unknown subjects 

 in the hospital ward the clinician should naturally use the constants 

 based on our 136 men, not on the 72 of the Gephart and Du Bois 

 selection or the 64 others. The same is true of the 103 women as com- 

 pared with the two subseries of 35 and 68 individuals. 



Since prediction constants based on these series, the largest avail- 

 able up to the present time, will be used in the calculation of controls, 

 it seems desirable to determine the error of prediction of the heat- 

 productions of the individual subjects, considered unknown, from 

 prediction constants based on the series as a whole. If we follow the 

 old practice of estimating the metabolism of a subject by multiplying 

 his body-weight by the average heat-production per kilogram of body- 

 weight, or his body-surface by the average heat-production per square 

 meter of body-surface, we employ the following average values per 

 24 hours : 



For men, # = 136: 



Mean calories per kilogram 25.697 



Mean calories per square meter of body-surface by height-weight chart 925.471 



For women, iV = 103: 



Mean calories per kilogram 24.457 



Mean calories per square meter of body-surface by height-weight chart 850.010 



If, on the other hand, we desire to use the method proposed in 

 this paper of predicting heat-production by use of regression equations, 

 we have the following: 



For men : 



h = 617.493 + 15.824 w h= -254.546 + 1070.454 a . 



D 



For women : 



A =884.528+ 8.227u> h= 333.618+ 638.610o . 



D 



