330 



MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



[Vol. XV, 



ranges, they agree in the main with the data already presented on the efficiency of the tests in 

 differentiating officers from men and the latter from institutional feeble-minded subjects. 

 There are certain exceptions, however. Tests 4 and 5 furnish a larger proportion of total score 

 with low than with high men, yet are very valuable in the higher ranges. Test 7 contributes 

 more to total score with high than with low subjects, yet has relatively low value in the higher 

 ranges. 1 



Section 3. — Proportion of zero and perfect scores. 



A large proportion of zero scores indicates either that a test is too difficult or that the 

 instructions are not simple enough; a large proportion of perfect scores, that the test is probably 

 not sufficiently difficult in the higher ranges of intelligence. Table 10 shows the per cent of 

 zero and perfect scores for officers and unselected men. 



Table 10. — Per cent of zero and perfect scores made by officers and enlisted men. 



Percent of zero scores. 



Test. 



1. 



2. 

 3. 

 4. 

 5. 

 6. 

 7. 

 8. 

 9. 

 10 



921 unse- 

 lected pri- 

 vates (Dix). 



Per cent. 

 9.7 

 8.0 

 36.0 

 9.8 

 13.1 

 21.1 

 27.8 

 31.9 

 23.5 

 12.2 



670 officers 

 (Lee). 



Per cent, 



4.2 

 .1 

 .3 

 .4 

 .9 

 3.4 

 2.2 

 .3 



Percent of perfect 

 scores. 



921 men, 



unselected 



(Dix). 



Per cent. 

 8.4 

 2.5 

 2.0 

 .3 

 .3 

 1.1 

 2.1 

 2.9 

 1.3 

 1.1 



1,051 offi- 

 cers (Dix). 



Per 



cent. 



34.5 



8.1 



12.4 



.5 



.9 



4.1 



8.1 



11.3 



1.2 



.6 



The above table shows that for unselected men the per cent of zero scores is very low for 

 tests 1, 2, and 4, low for 5 and 10, very high for 3 and 8, and rather high for 6, 8, and 9. Even 

 officers often fail to score on tests 3, 8, and 9. Few privates make a perfect score on any except 

 test 1, which for officers also is by far the easiest of the 10 tests. The fact that tests 3 and 8, 

 which yield a high percentage of perfect scores, yield also an exceptionally high proportion of 

 zero scores, indicates that the instructions for these two tests are confusing. 



At Camp Lee 2,500 examination records (500 per each form) were tabulated to show the 

 percentage of zero scores made in the different tests by unselected men at various levels of in- 

 telligence. The most important results are summarized in Table 11 : 



Table 11. — Per cents, making zero scores at different levels of intelligence. 



> As indicated on page 341, test 7, as revised for the alpha examination, is a much 

 better test than the original form. Part of this improvement is due to a change in 

 scoring. 



