A CRITIQUE OF THE BODY-SURFACE LAW. 177 



as a basis of the prediction of the heat-production of a subject, we note 

 the following points from the two major series of each sex (series 

 IV-VII, tables 60-62, 66-68). 



1. In testing the two bases of prediction, body- weight and body- 

 surface, by the average deviation with regard to sign of the predicted 

 from the actually observed values, we find that in predicting by the 

 use of mean heat-production per unit of weight and of mean heat- 

 production per unit of surface area, body-surface gives the lower 

 average deviation in three of the four series (table 60). When pre- 

 diction is made by means of the linear regression equations, body- 

 surface gives the lower average deviation in all four series (table 66). 



2. In testing the two bases of prediction by means of the average 

 deviation without regard to sign of the predicted from the observed 

 values, we find that in predicting from mean heat per unit of weight 

 and from mean heat per unit of area, body-surface is the better basis 

 of prediction in all four cases (IV-VII, table 61). In predicting by the 

 use of equations we find that surface is the better basis of prediction in 

 three of the four cases, but slightly worse than body-weight in series 

 V, table 67. 



3. In testing the two bases of prediction by the square root of 

 mean-square deviation of the predicted from the observed values, we 

 find that in predicting from mean heat-production per unit, body- 

 surface gives lower deviations from the actually measured heat- 

 productions than body- weight (table 62). In predicting by equations, 

 body-surface gives the closer agreement of prediction with observation 

 in two of the series (IV, VI), but the two methods are, practically 

 speaking, equally good in the other two series (V, VII, table 68). 



The net result of this analysis seems to be that metabolism can be 

 predicted more accurately from body-surface than from body-weight. 

 The difference between these two means of prediction depends in a 

 very large degree upon the method of calculation used, and somewhat 

 upon the criterion of accuracy of prediction adopted. With the best 

 methods of calculation the difference between the accuracy of prediction 

 from body-weight and that from body-surface is not very large. 



8. FURTHER TESTS OF THE VALUE OF BODY- WEIGHT AND BODY-SURFACE 

 FOR ESTIMATING TOTAL HE AT- PRODUCTION. 



The practical importance of the solution of the problem of predict- 

 ing the metabolism of the individual with the highest attainable degree 

 of accuracy is so great that we shall apply one further test of the rela- 

 tive value of body-weight and body-surface area as measured by the 

 Du Bois height-weight chart. In the preceding tests we have adhered 

 strictly to the procedure which is theoretically the best and which 

 fulfills exactly the conditions to be met in practice. That is, in the 

 case of a subject whose metabolism is assumed to be unknown, we have 



