THE METHOD OF AGE GRADATION 101 



The investigation can be made with more pre- 

 cision if the curve of distribution be based upon the 

 mental quotient instead of the mental age, for we 

 should then anticipate fairly good correspondence 

 between the curves of distribution of the different 

 age-levels. The mental quotients for each age-level 

 would then be grouped together in 10 per cent, 

 ranges, i. e., we should have first the children with 

 mental quotients ranging from 0.91 to 1.00 and 1.00 

 to 1.10 that would form the compact middle group, 

 then on either side of them groups of rapidly dimin- 

 ishing frequencies, those with mental quotients .81 

 to .90, .71 to .80, etc., below, and those with quotients 

 1.11 to 1.20, 1.21 to 1.30, etc., above. 



In the older form of the Binet-Simon scale the 

 number of tests assigned to each year differed. In 

 1911 Binet put five tests in every age; it is to be 

 recommended that this idea of uniformity be fol- 

 lowed in the future because the computation of the 

 final status is much simplified in that way. 25 



(c) The extension of the system. In the next 

 place the system of tests is to be extended beyond 

 its present limits and in different directions. 



Thus far the lack of tests has been most seriously 

 felt in the upper years. The tests that Binet and 

 others have devised above the llth year have been 

 thus far quite tentative and provisional; at the best 

 they could furnish us the necessary supplementary 

 material for the ascertainment of mental ages 10 

 and 11, but they absolutely fail to provide a direct 



20 Cf. also the provisional new arrangement of Bobertag in Ap- 

 pendix II. 



