60 PSYCHOLOGICAL METHODS OP TESTING INTELLIGENCE 



tingency means the degree of correspondence be- 

 tween two intersecting groups. If all children 

 pedagogically retarded should also exhibit mental 

 retardation, or if the converse should occur, then the 

 contingency would be absolute (= 1) ; if among the 

 pedagogically retarded children there were rela- 

 tively no more mentally retarded than among the 

 children with normal or with superior school attain- 

 ments, then the contingency would be = 0. The de- 

 gree of correspondence can be shown by a number 

 lying between and 1, termed the coefficient of con- 

 tingency. 



From the above tables I have computed the follow- 

 ing values : 



Degree of 



First Factor Second Factor Correspondence 



Pedagogical retardation Mental retardation 0.41 



Mental retardation Pedagogical retardation 0.30 



Pedagogical advance Mental advance 0.45 



Mental advance Pedagogical advance 0.19 



The index of correspondence, then, is but moder- 

 ately large at best and even that only when we pass 

 from school ability to intelligence, not in the re- 

 verse direction. Hence, to draw conclusions about 

 school status from varying intellectual abilities is 

 even less permissible than to draw conclusions about 

 intellectual ability from varying school status. 



In his mass-experiment, Goddard (48) came to a 

 similar result. He found that more than the half of 

 all the children tested were in classes that did not 

 correspond to their mental age most of them, as a 

 matter of fact, in a lower and only a few in a higher 

 class. 



Bobertag compared mental age with the school 



