78 PSYCHOLOGICAL METHODS OF TESTING INTELLIGENCE 



intelligence upon all 6-year-old children when they 

 entered school, then the designations " retarded one 

 year" or "advanced one year" would have an un- 

 equivocal meaning. 



TABLE X 



FREQUENCY OF MENTAL RETARDATION IN DIFFERENT FORMS OF FEEBLE- 

 MINDEDNESS AND DIFFERENT CHRONOLOGICAL AGES 



r- Not Feeble-minded-^ r-Doubtfully Defective-^ 



Retardation 1 Yr. 2 Yrs. 3 Yrs. 1 Yr. 2 Yrs. 3 Yrs. 4 Yrs. 



8 6 11 13 4 



975 13 



Chronological 

 Age 



10 2 3 



11 1 1 



12 1 1 



13 1 



/ Mjorons > , Imbeciles ^ 



1234 12345 



Retardation Yr. Yrs. Yrs. Yrs. Yr. Yrs. Yrs. Yrs. Yrs. 



[84 10 2, c 6 21 921 



Chronological 9 15 2 8 30 8 2 



- 10 57 754 



Age 11 5 1 2 



12 21 12 



But it is another matter when we have to consider 

 children of quite different ages or when we want to 

 express the degree of backwardness in a formula of 

 general validity. The value based on absolute dif- 

 ference, if given by itself, may mean very different 

 things, so that at least the chronological age ought 

 always to be stated to enable the reader to figure out 

 the degree of importance to be attached to the dif- 

 ference. To what prolixity of statement this 

 method leads one may be illustrated by the follow- 

 ing sentence from Chotzen (pp. 493-4) : "Children 

 of 8 to 9 years can suffer a deficiency of one year, 

 those of 10 to 12 years one of two years without 



