328 



MEMOIRS NATIONAL ACADEMY OF SCIENCES. 

 Section 1. — Differentiation between officers and enlisted men. 



[Vol. XV, 



One of the most striking indications of the validity of examination a as a whole was the 

 large difference in median scores of officers and enlisted men. These differences are illustrated 

 by the following figures : 



Military group. 



Officers (all camps) 



Officers' training camp students 



Sergeants (Taylor) 



Corporals (Taylor) 



Enlisted men°(all camps) 



Number. 



5,563 



16, 798 



196 



243 



65.267 



Median 

 score. 



296 

 269 

 232 

 209 



154 



In order to disclose the relative value of the separate tests of examination a in differenti- 

 ating between officers and men, the average scores of 300 American-born privates were compared 

 with those of 703 officers. Table 6 gives the facts for comparison worked out at Camp Dix. 

 The sixth column gives for each test the P. E. of the difference between means, and the next to 

 the last column gives the ratio of the difference between means to the P. E. of this difference 

 This ratio is not only an expression of the certainty of the difference between means, but may 

 be taken as an index of the value of the test in differentiating between officers and men. The 

 figures of the last column give the rank order value of the tests on this basis. 



Table 6. — Differentiation between officers and enlisted men by the separate tests of examination a. 



1 Average ratio. 



A similar comparison was made of 164 captains and 200 A or B men (Lee data) in order to 

 find whether some of the tests excelled others in discriminating between officer material and 

 privates having about the same intelligence. The results of this comparison are shown in 

 table 7. It will be seen that the officers excel in tests 5 and 6, and A and B privates in tests 

 4, 7, and 10. The differences, however, are so small as to lack significance. It does not appear 

 that the intelligence of officers differs qualitatively in any marked degree from that of A and 

 B privates. 



Table 7. — Comparison of records of captains and A and B men in examination a. 



Test. 



164 captains (Lee). 



Mean. 



S. D. 



200 A and B men (Lee). 



S. D. 



P. E.of dif- 

 ference. 



Ratio of dif- 

 ference to 

 P. E.of dif- 

 ference. 1 



1. 

 2. 

 3. 

 4. 

 5. 

 6. 

 7. 

 8. 

 9. 

 10 



9.00 

 8.93 

 14.29 

 13.00 

 32.6 

 29.7 

 7.1 

 10.83 

 25.5 

 25.3 



1.4S 

 2 22 

 Sjto 

 6.00 

 6.24 

 7.78 

 2.08 

 4.04 

 10.80 

 6.44 



8.91 

 8.93 

 14.14 

 14.0 

 30. 54 

 27.9 

 7.6 

 11.2 

 25.7 

 26.5 



1.37 

 1.91 

 4.40 

 2.34 

 3.73 

 6.96 

 1.72 

 3.46 

 7.96 

 6.16 



0.090 

 .142 

 .333 

 .330 

 .348 

 .497 

 .129 

 . 252 

 .610 

 .433 



0.99 



.0 



.42 



S.JO 



5.64 



3.58 



i-SS 



.55 



.SI 



e.ss 



1 Italics in the last column indicate that A and B men score higher than officers; roman type means that 

 the difference is the other way. 



