468 MEMOIRS NATIONAL ACADEMY OF SCIENCES. [Vol. xv, 



consequently the group makes a very poor showing. The Artillery privates, on the other hand, 

 as a group have enough intelligence to understand the test, and, owing to its all-or-none 

 nature, make very high scores. The result is that the two groups are very sharply differ- 

 entiated. 



The order of tests in differentiating "poorest" Infantry from standard differs from that 

 in the differentiation of "men of low military value" from standard chiefly in the positions 

 of tests 4, 6, and 7. Test 7 ranks last in the latter case and first in the former. Tests 6 and 4 

 show the same almost complete exchange of positions. There is probably no other explanation 

 than the one given in the case of the alpha test — viz, that the standards of selection of these 

 two groups have been qualitatively different. 



The comparison of beta tests on the basis of the Camp Meade data adds another degree 

 of variation to the results. The correlations between military efficiency and score which it has 

 been possible to obtain from these data are generally higher than the corresponding correlations 

 for alpha tests. This, however, does not mean that the beta tests are necessarily better 

 measures of military efficiency than the alpha tests. It is merely an apparent superiority due 

 probably to the fact that a greater proportion of the individuals tested by beta fall within the 

 effective ranges of the tests than is the case with the alpha group. There is not much common 

 ground upon which a comparison of alpha and beta can be made. Both are effective only 

 within special ranges which do not overlap to any great extent. 



Correlation ratios for military value on scores indicate that tests 4 and 6 are the best 

 tests of the set. This conclusion agrees with the result of the comparison of "men of low mil- 

 itary value' ' with standard, referred to above, but contradicts the result of the comparison of 

 "poorest" Infantry with the standard. 



