THE METHOD OF AGE GRADATION 47 



least of all in Goddard's own results. Bather is it 

 true, as is evident from closer consideration, that 

 the symmetrical curve above mentioned owes its 

 existence to the fact that the varying results of dif- 

 ferent years practically compensate each other. 8 In 

 truth, the results of almost all who have tried out 

 the Binet-Simon method, regardless of the nation- 

 ality tested, agree that the series set for the lower 

 years are too easy, those for the higher too difficult. 

 The evidence for this, so far as known to me, I have 

 introduced in Table II. 



From Goddard's (48, p. 243), Bobertag's (40, II, Table I) and 

 Miss Johnstone's 9 raw tables I have computed the percentages of 

 frequency for American, German and English children. Goddard's 

 data I have figured for each year separately ; those for the two 

 other investigators by bringing two or three years together, on 

 account of the smaller number of cases (Table II). It will be 

 seen that in the lower years many more are 'advanced' than there 

 should be : in Goddard and in Johnstone the advanced outnumber 

 not only the retarded, but even the 'at-age' children. Thus, for 

 instance, in Goddard more than half the 5-year old children attain 

 a mental age of G years or over clear evidence that these tests 

 are much too easy. In Bobertag the lack of symmetry is not so 

 pronounced. 



The area of excessive percentage of advanced children ( and thus 

 of excessive ease of the tests) extends in Goddard through the 7th, 

 in Bobertag through the 8th year; in Johnstone it has not en- 

 tirely disappeared even at the 9th year. Then comes a sudden re- 

 versal : in the higher years the number of retarded children in- 

 creases : the tests are therefore too hard. 



With the 155 subjects examined by Bloch and Preiss (38) there 

 was made at the outset a selection such that only children of 

 medium ability and school performance were tested. Consequently, 

 retardation in mental age appeared almost not at all, but advance- 

 did appear, though in diminishing frequency with advancing age. 



8 Ayres (31) calls attention to this point in his critique of 

 Goddard. 



9 In Miss Johnstone's original work (52) the quantitative data 

 are not given sufficiently clearly, but these data are given by 

 Binet (36, p. 196) where will be found a table of distribution for 

 146 Sheffield school girls as imparted in a letter from Miss John- 

 stone. 



