J. A. Harris and F. G. Benedict 269 



* 



f body surface area as estimated by some one of the various 

 brmulas which have been proposed for this purpose. 



When observations for a number of days are available, and 

 /hen it is desirable to define the basal metabolism of the indi- 

 idual more precisely than can be done as the result of experimen- 

 ation for 1 day, the question naturally arises whether the aver- 

 ge of the daily means or the minimum daily mean shall be used 

 o represent the basal metabolism of the individual. The exact 

 lethod of calculating the average and the standard deviation 

 herefore requires consideration. 16 



In a preceding publication 1 we used the average of the daily 

 leans for the determination of the population constant. Our 

 rotocols of data 17 show these values and indicate the number of 

 ays and the total number of periods upon which they were based. 

 : One of our helpfully critical correspondents has suggested that 

 . may be quite improper to lump together and treat as of equal 

 alue basal metabolism constants for individual subjects some of 

 hich rest upon an observation for only a single day while others 

 epend upon many days measurements. 



This criticism has probably also occurred to others. It seems 

 ssirable, therefore, to consider the problem of the best method 

 : deducing a constant for a series of individuals a population 

 mstant from the experimental readings. 



There are seven possible ways of determining the statistical 

 mstants of a series of metabolism measurements some of which 

 .ist upon work for but a single day while others depend upon 

 iveral days observation. 



A. The average of the daily averages may serve as the units 



presenting the individuals. 



If the measured metabolism is variable it seems illogical, as our 

 ^respondent suggests, to treat the constant obtained from an 

 oservation for a single day as equal in value to that deduced from 

 :number of days observation. The selected constant may, there- 

 :re, be (1) used only once in the calculation of the statistical 

 &quot;nstant for the population; (2) may be weighted with the num- 



16 While we have elsewhere proposed the use of multiple prediction equa- 

 tins for calculating the basal energy requirements, the consideration of 

 ie most suitable method for the determination of the statistical constants 

 1 represent the individual is pertinent, since the calculation of these equa- 

 ims involves the determination of the means and standard deviations. 



17 Harris and Benedict, 1 Tables A to D. 



