454 



MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



[Vol. XV, 



Table 125. — Means and standard deviations of the mean for scores in the eight alpha tests made by various military groups. 



A. 984 "UNSELECTED" CASES. 



B. 304 NONCOMMISSIONED OFFICERS OF THE FIFTY-SECOND, FIFTY-THIRD, AND FIFTY-FOURTH FIELD ARTIL- 

 LERY. CAMP TRAVIS. 



C. 5S1 NONCOMMISSIONED OFFICERS OF THE NINETEENTH INFANTRY, CAMP TRAVIS. 



D. 247 CASES AMONG "10 BEST" PRIVATES IN EACH COMPANY OF THE FIFTY-SECOND, FIFTY-THIRD, AND FIFTY- 

 FOURTH FIELD ARTILLERY, CAMP TRAVIS. 



E. 153 CASES AMONG "10 BEST" IN EACH COMPANY, NINETEENTH INFANTRY, CAMP TRAVIS. 



F. 165 CASES AMONG "10 POOREST" PRIVATES IN EACH COMPANY, FIELD ARTILLERY, CAMP TRAVIS. 



G. 75 CASES AMONG "10 POOREST" PRIVATES IN EACH COMPANY OF THE NINETEENTH INFANTRY, CAMP TRAVIS. 



II. 85 CASES IN "SUPERIOR" GROUPS, INFANTRY, CAMP KEARNY. 



I. 68 CASES IN "AVERAGE "GROUPS, INFANTRY, CAMP KEARNY. 



J. 50 CASES' IN "INFERIOR" GROUPS, INFANTRY, CAMP KEARNY. 



K. 48 CASES OF "LOW MILITARY VALUE," CAMP CUSTER. 



The material differs so much on account of the methods of obtaining it, as indicated above, 

 that no one method is applicable to all of it. 



A customary method of comparing groups of individuals makes use -of the ratio of the 

 difference between their means to the probable error of that difference. Such ratios have been 

 calculated for all of the Travis, Kearny, and Custer material (table 127). Different values of 



