THE CHANCES OF DEATH 99 



cal, chemical, biological, and mathematical investigations 

 are comparatively few in number. The literaturei of 

 science shows nothing clearer than that the same type 

 of curve frequently serves to describe with complete 

 accuracy the quantitative relations of widely different 

 natural phenomena. As a consequence, any proposition 

 to conclude that two sets of phenomena are causally or 

 ill any other way fundamentally related solely because 

 they are described by the same type of curve is of a very 

 doubtful validity." 



Henderson has put Pearson's five components together 

 in a single equation, as follows : 



7 7525 

 / I— 715\ 0.2215 (a;— 71.5) —[.05524 (a;— 41.5)]' 



iiA«x=15.2ll 35-^) « +5.4e 



— [.09092(a; — 22.5)P 

 + 2.6e +8.5(2;— 2)'^^''^^ — .3271(a; — 3) 



Henderson says regarding this method of Pearson's 

 for analyzing the life table : " . . . it is diflScult to lay a 

 firm foundation for it, because no analysis of the deaths 

 into natural divisions by causes or otherwise has yet been 

 made such that the totals in the various groups would 

 conform to those frequency curves." The italics in this 

 quotation are the present writer's for the purpose of em- 

 phasizing the crucial point of the whole matter. 



Now it is altogether probable that one could get just 

 as good a fit to the observed dx line as is obtained by 

 Pearson's five components by using a 17 constant equa- 

 tion of the type 



y=a + bx + cx' + dx' + ex* +fx? + gx>+ +nx^* 



