110 PSYCHOLOGICAL METHODS OP TESTING INTELLIGENCE 



the departmental teacher ranks them at the end of 

 the term on the totality of their work in his subject : 

 finally, all these ranks in different subjects are com- 

 bined into a rank-order for the school certificate in 

 which every pupil is assigned his "class-place." 



Since these rank-orders are always available, it is 

 but natural to employ them for our problem, and 

 this is what actually happened very often in the 

 early stages of the experimental study of intelli- 

 gence. Thus, for example, Ebbinghaus (5) divided 

 his subjects into three sections on the basis of their 

 class-marks in order to determine whether the dif- 

 ferent groups responded with different degrees of 

 success to his completion tests. Other investigators 

 had the teachers select a number of ' good ' and 'poor' 

 scholars in order to make comparison of their be- 

 havior under experimentation. 



Yet, however convenient this ever-ready classifica- 

 tion may be, it is not at all adequate for our pur- 

 poses, because the implicit assumption that under- 

 lies such uses of the class-marks that school per- 

 formance is an absolutely accurate indication of in- 

 telligence is unjustified. The results obtained by 

 the Binet- Simon method have already shown this 

 (see p. 59), and other statistical data will confirm it. 

 As a matter of fact, every school man who is blessed 

 with psychological insight, knows it himself. 



We need, then, a rank-order that is based directly 

 upon the degree of intelligence of the pupils. 



Such an order does not exist in the ordinary school 

 system, and must therefore first be created ad hoc. 

 There are available, again, two different ways of ac- 

 complishing this aim : either the teacher, on the basis 



