518 MEMOIRS NATIONAL ACADEMY OF SCIENCES. [volxv. 



Table 158. — Comparison of officers by camps — Ratio of the differences between means to probable errors of differences. 



Comparison of branches. — Table 159 gives the detailed distribution of officers of certain 

 main branches of the service. Figure 22 presents graphically these data summarized by letter 

 grades for purposes of rough comparison. Again the dividing line between B and C has been 



o sf.y.5% 2 ?9? 



ZZE 



67 3-7'. 



ENGINEERS 



■■■f-\:':\\\ 



VZZL 



A:::i :v h-v-: : : 



60 Z>i. 



ARTILLERY 



0.1'/. 1 9-6^ ■ 33 0^ 



f77777J 



Al\j. 



INFANTRY 



0.2 j. 2AAJ. 



vmrn 



Z>k>Af. 



390 1 /. 



Q. M. 



37. 367 1. 



3&fi# 



34 0% 



///////////):■■ 



36 2% 



290/. 



Z3 



250'/. 



Z3 



MEDICAL 



DENTAL 



57-4/. 



v////////////////\ 



24 \"f. 



i- 



BELOW B 



c 



m 



ias# 



VETERINARY 



ft B OR 



A 



a 



Fig. 22. Comparison of olhcers by branches, showing percentages in each letter grade. Branches Irom all four camps combined. Engineers, 

 336; artillery, 680; infantry, 2,050; quartermaster corps, 470; medical, 639; dental, 116; veterinary, 54. 



stressed as most important. On this basis of comparison we find the various branches separated 

 for the most part by quite distinct steps and arranged in the following order of excellence: 

 Engineer, Artillery, Infantry, Quartermaster Corps, Medical Corps, Dental Corps, Veterinary Corps. 

 The differences between the extremes of these groups are very striking. On the one hand, we 

 note the engineer and artillery officers with 90.2 per cent of A and B grades and 85.6 per cent, 

 respectively, and, on the other hand, the medical, dental, and veterinary corps with 63 per cent, 



61.2 per cent, and 42.6 per cent, respectively. The same order of excellence appears if we con- 

 sider only the percentages making A grades, though the disparity in favor of the highest groups 

 is even more marked. Thus we find the engineer and artillery officers with 67.3 per cent and 



60.3 per cent of A men, respectively, as contrasted with the medical, dental, and veterinary with 

 29 per cent, 25 per cent, and 18.5 per cent, respectively. 



