STANDARD BASAL METABOLISM CONSTANTS. 227 



series of individuals to be used as a control in any specific instance; 

 (2) because of the well-known and large variations in the metabolism 

 constant from subject to subject the average value based on a small 

 group of individuals may be either too large or too small by an amount 

 determined by the probable errors of random sampling. 



It seems clear that some form of the selected-group method will fur- 

 nish the most satisfactory basis of comparison. Ideally one should find 

 a method which will combine all the advantages, and reduce to a mini- 

 mum all of the disadvantages, of the two methods hitherto employed. 



The results of the analysis in the preceding chapters have shown 

 that four factors need to be taken into account in estimating the basal 

 metabolism of a subject: sex, body-weight, stature, and age. 



The importance of body-weight in the selection of controls has been 

 very generally recognized, at least tacitly, by all those who have 

 expressed metabolism in terms of oxygen consumption, carbon-dioxide 

 excretion, or calories produced per kilogram of body-weight. While 

 the relation of stature to metabolism is not so obvious as that of body- 

 weight, it has been shown in Chapter IV to be a character of independ- 

 ent significance in the determination of metabolism. It has long been 

 known that metabolism is related to age. In Chapter V this relation- 

 ship has been expressed quantitatively. 



The method used here for the establishment of standard normal 

 metabolism constants is essentially an extension of the selected-group 

 method used earlier for various comparisons at the Nutrition Labora- 

 tory. Instead of using the empirical average heat-production of an 

 actually observed group of individuals, we shall give the ''smoothed" 

 or "graduated" values for groups of given age, stature, and body- 

 weight as determined from equations based on all the available data. 

 We thus obviate, as far as possible, the two main objections to the 

 selected-group method : (a) the possibility of the influence of personal 

 equation in the selection of the normal values to be used as controls 

 in any specific case, and (6) the probable errors of random sampling 

 attached to the control constants. The rather detailed application 

 of the method in Chapters V, VI, and VII should have made the whole 

 theory perfectly clear. There remains, therefore, merely the restate- 

 ment of the equations and the tabling of a series of standard constants 

 to be derived from them in the form most convenient for practical use. 



As shown in Chapter VI, p. 190, the multiple prediction equations 

 based on the total adults of the two sexes are 



For men h = + 66.4730 + 13.7516 u;+5.0033s -6.7550 a 



For women h = +655.0955+ 9.5634 w + 1.8496 8-4.6756 a 



where h = total heat-production per 24 hours, w = weight in kilograms, 

 s= stature in centimeters, and a=age in years. The evaluation of 

 these equations, which are used in the calculation of the theoretical 



