STANDARD BASAL METABOLISM CONSTANTS. 229 



meter is about the limit of accuracy. To retain tenths of kilograms is 

 certainly weighing with a degree of refinement hardly justified by the 

 continually changing state of the experimental object. Finally, when 

 individuals are recorded to the nearest year of age we may remember 

 that they are on an average a quarter of a year older or younger than 

 the age to which they are assigned. 



Against these objections is to be urged the fact that measurements 

 which are not made with great refinement are very apt to lack essential 

 accuracy. Since these are the divisions of the scales which have been 

 most generally employed by physiologists it has certainly not seemed 

 desirable to replace them by coarser ones. Furthermore, it must be 

 noted that our equations are not based upon a few observations, but 

 upon over 100 determinations for each sex. Therefore, as a basis of 

 generalization, they have a much higher degree of accuracy than any 

 single observation or group of a small number of observations. 



The sources of error in using the multiple prediction tables are two. 



(1) The tables themselves are based upon a finite number of 

 observations. In comparison with physiological measurements as a 

 class, the number of measurements is very large; biometrically con- 

 sidered it is small. Every constant in these equations is therefore, 

 somewhat too large or somewhat too small because of the innate varia- 

 bility of human individuals. If another group of subjects were added 

 to the series upon which these tables are based the factors would be 

 slightly changed. The constants are subject to revision with increasing 

 intensiveness or extensiveness of work, just as all physical and chemical 

 constants are. 6 Until more data are available they must be taken 

 as they are, with the understanding that the standard has its probable 

 error, just as have the individual metabolism measurements which 

 will be compared with it. 



(2) As we have repeatedly emphasized in the foregoing pages, every 

 individual metabolism measurement considered as a basis for general- 

 ization concerning the peculiarities of the individual upon which it is 

 based (e.g. physical characteristics, pathological state, etc.) has a large 

 probable error. Thus one can not compare the metabolism of a single 

 individual of any specified type with the standard constant and use 

 it as a basis of generalization. It is only when a series of individuals 

 of the specified type are considered that generalizations may be drawn. 



From the standpoint of arithmetical technique, the tables probably 

 correctly represent the results of the largest series of determinations on 

 normal men and women with an error of not over 1 calorie per 24 hours. 7 



6 We plan later to prepare a revised edition of these tables based upon more extensive data. 



7 The results could have been given in such a form that the final constants would have been 

 arithmetically correct to less than a single calorie per 24 hours had decimal places been retained 

 in the tables. This seemed a quite needless refinement. Those who desire may derive the theo- 

 retical values to more places directly from the equations. The theoretical values in the series 

 of illustrations in this chapter were determined in this way. 



