42 



Americcm Statistical Association. 



Table I.— Givinc: the measures of 749 students of Amherst College at 

 two intervals of three years and six months, and at an averaj^e age of 19 

 years and two months at the rirst observation, showing their physical 

 development during this period. 



Number of men measured, 



" " increased in all items, .... 



" " decreased in some items. . . 



" " both same and increased items, 



" " both same and decreased items, 

 Number of items secured, 



" " showing increase, 3,972 



" " same Freshman and Senior year, 



" " less in Senior year, 701 



Greatest individual gain. 

 Averages of increased men 

 Per cent of decreased items I 



25.00 

 4.50 

 20.13 



Some statistics have been gathered showing the differences 

 between the ''average" and the "mean." 



Sir John Herschel has said ''an average may exist of the 

 most different subjects, as the height of honses in a town, or 

 the size of books in a library. It may be convenient to con- 

 vey a general notion of things, but it involves no conception 

 of a natural and recognizable central magnitude, all differ- 

 ences from which ought to be regarded as deviations from a 

 standard. The notion of a mean, on the other hand, does 

 imply such a conception standing distinguished from an 

 average by this feature, namely, the regular march of the 

 groups, increasing to a maximum, and then again diminish- 

 ing. An average gives us no assurance that the future will 

 be like the past ; a mean may be reckoned on with the most 

 implicit confidence." 



