A CRITIQUE OF THE BODY-SURFACE LAW. 



169 



prediction from area by the Meeh formula. Again the results indicate 

 the superiority of the Du Bois height-weight chart as a basis of pre- 

 dicting the metabolism of an unknown. 



Table 62 gives (in terms of the square root of mean-square devia- 

 tion of the predicted from the actual values) a comparison of the results 

 of predicting by the three different means. The square root of the 

 mean-square deviation of the calculated from the actually measured 

 metabolism is in all series greater in prediction from weight than it is 

 in prediction from the height-weight chart. This method, like the 

 two preceding, therefore, justifies the conclusion that (as an empirical 

 basis for the prediction of the heat-production of an individual, on the 



TABLE 62. Square root of mean-square deviation of total heat-production as predicted from 



the mean heat-production per unit of body-weight and surface in standard 



series from the actual heat-production. 



assumption that heat-production bears a definite ratio to some physical 

 character) the Du Bois height-weight chart measure of body-surface 

 area furnishes distinctly better means of prediction than does body- 

 weight. In the series of 64 individuals in which prediction is made 

 from the Gephart and Du Bois selection the square root of mean 

 square errors expressed as a percentage of the mean of the measured 

 heat-production of the individuals stand as 11.5 : 7.8; in the Gephart 

 and Du Bois selection they stand as 8.1 : 6.8; in the first female series 

 as 14.9 : 9.0; and in the second female series as 24.5 : 13.0 per cent. 

 We now turn to the prediction of metabolism by means of a mathe- 

 matical equation fitted to a series of observations. Because of its 

 simplicity and its direct relation to the correlation coefficient we have 

 naturally first availed ourselves of the linear regression equation. 

 These follow: 



