J. A. Harris and F. G. Benedict 273 



,vely small, being less than 1 per cent in the three comparisons. 

 11 differences are less than twice as large as their probable errors. 

 It is clear from the foregoing constants that practically it is 

 nmaterial whether the population means are calculated from the aver- 

 ges of the individual subjects, from the averages weighted with the 

 umber of days, or with the square root of the number of days, or 

 hether they are determined directly from the daily observations. 23 

 From Table VII it appears that the standard deviations obtained 

 y weighting the individual means with the square root of the 

 umber of days or with the number of days are lower than those 

 ilculated without weighting. 



We now have to consider the constants deduced from the mini- 

 mm values of the daily metabolism. The results are given in 

 able VIII. Limiting our attention for the moment to a com- 

 arison of these constants among themselves we note that, in 

 hatever units measured, the mean metabolism calculated by 

 -eighting with the square root of the number of days is always 

 wer than the constant obtained without weighting. When the 

 linima for the individuals are weighted with the number of 

 ays instead of with the square root of the number of days the 

 ifference between the weighted and the unweighted value is even 

 reater, amounting to 69.6 calories of total daily heat produc- 

 on, -0.579 calories per kilo, and 32.03 calories per square 

 leter of surface area. These differences correspond to relative 

 ifferences of 4.49, 2.35, and 3.63 per cent of the unweighted con- 

 ,ants. They show that if an absolute minimum, i.e. the one single 

 ay with the lowest average of metabolism measurements, for each 

 idividual is adopted, the constants for a population will depend to 

 considerable extent upon the number of days observation for each 

 idividual. 



Table IX compares the percentage change in the population 

 Dnstant due to weighting when the population constant is calcu- 

 ited from means and from minima. For all three units of metab- 



23 While this is the result for the large series of data in hand the calcu- 

 .tion of the population constant from daily observations by weighting 

 ith the number of days is not to be generally recommended since in series 

 i which the number of individuals is small the population average may be 

 )o greatly influenced by repeated observations on one or a few intensively 

 udied individuals. 



