AMERICAN MEN OF SCIENCE 



541 



as the list resulted, are at Harvard Uni- 

 versity; about 10 per cent, of them made 

 the arrangement, which is about 30 per cent, 

 of those asked. Seventeen of the 39 scien- 

 tific men at the University of Chicago were 

 asked to make the arrangement, of whom 

 fifteen accomplished it and two did not. Or 

 38 per cent, of all its men made the arrange- 

 ment, who were 88 per cent, of those asked. 

 The numbers are in most cases too few to 

 give a correct measure of the cooperativeness 

 in such a scheme of the different institutions, 

 but, so far as they go, they are not altogether 

 without interest. They are not, however, 

 printed here for that purpose, but in order 

 to show the geographical distribution of those 

 who made the arrangement. It appears that 

 different institutions are fairly well repre- 

 sented, there being no great preponderance 

 of any one of them. Of the 120 who made 

 the arrangement 89 are connected with the 17 

 institutions given in the table, although these 

 institutions contain only 450 of the 1,000 sci- 

 entific men. They, however, have, as will be 

 shown later, a much larger proportion of the 

 more eminent scientific men. 



Those who made the arrangements are not 

 likely to possess equal information, impartial- 

 ity and good judgment. If there were only 

 two arrangements of each group it would not 

 be possible to decide objectively which is the 

 better. We have, however, ten arrangements, 

 and the average is more likely to be correct 

 than any one of them. The conditions are 

 the same as in the case of observations in the 

 physical sciences. As the personal equation 

 of the astronomer is determined by comparing 

 his observations with those of other astron- 



omers, so here we can measure the accuracy 

 of judgment of each observer by determining 

 how far it departs from the average judgment. 



I have counted up the departures of each of 

 the ten observers from the average result for 

 one of the groups, namely, the fifty psychol- 

 ogists. The data are given in Table IV. by 

 groups of ten. 



The observer A is always more accurate 

 than any other observer, except in one case 

 in the fifty. The validity of judgment of the 

 ten observers varies from 7.9 to 17.26, or about 

 as 1:2, which is approximately the yariability 

 that I have found in normal individuals in 

 other mental traits, such as accuracy of per- 

 ception, time of mental processes, memory, etc. 

 The departures from the mean reliability of' 

 judgment, given in the last line of the table, 

 indicate that accuracy of judgment tends in 

 a general way to follow the normal distribu- 

 tion of the probability curve, though with so 

 few cases this may be accidental. As the 

 validity of the judgments varies to a measured 

 degree, the arrangements made by the indi- 

 viduals could be weighted. I have not under- 

 taken the somewhat tedious calculations neces- 

 sary ; they would not considerably alter . the 

 order, but would make it somewhat more exact, 

 at the same time decreasing the probable 

 errors. 



There is here measured for the first time, 

 I think, the accuracy or reliability of judg- 

 ment. This is obviously a complex and im- 

 perfectly analyzed trait, depending on a large 

 number of varying conditions. A man's judg- 

 ment may be good in some directions or from 

 certain points of view, and bad in other ways. 

 Still we understand vaguely what is meant by 



TABU; iv. MEASUREMENTS OF THE ACCUBAOT OP JUDGMENT OF TEN OBSERVERS 



