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MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



[Vol. XV, 



Table 154 gives more detailed distributions and constants for certain groups of candidate 

 officers in comparison with closely related officer groups. For this purpose the training camps 

 of two stations (Camp Devens and Camp Taylor) are shown in relation with officers at these 

 same camps. Similarly the students in Engineer officers' training camp at Camp Lee, which 

 drew from a considerable number of camps, are shown in comparison with the Engineer officers 

 from all four camps. Figure 20 presents graphically the data on the two groups from Camp 

 Devens. In all three combinations here shown a slight difference in favor of the officer group 



2h 



i i i i 

 O-49 



E 



.50-99 

 D 



I I I I I I I I 

 100-149 150-199 



c- -I c 



I I I I 



200-249 

 C + 



n 

 250-299 

 B 



i i I I I' I I I i i I 

 300-3491 350 -A 14 

 A 



SCORE 

 GRADE 



Pig. 20. Percentage distributions of officers ( ) and officer candidates ( ), Camp Devens. Officers, 1,117; officer candidates, 799. 



is indicated. Computing the probable errors of the differences between the means of the several 

 groups gives the following results: 



Difference of the means (Devens officers v. Officers' training camp) =6.6 P. E.Dift. 



Difference of the means (Taylor officers v. Officers' training camp) =2.6 P. E. dm. 



Difference of the means (Engineer officers v. Engineer officers' training camp) = 6.7 P. E.Difl. 



If we consider that a difference is great enough to carry conviction regarding its significance 



when it is at least 4 times the probable error of the difference, it is evident that two of the above 



