406 



MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



Table 63. — Form board and Stanford-Binet mental age (r— 0.480). 



[Vol. XV, 



Further abbreviation. — In camp examining it was found that the recommended short scale 

 (tests 2, 4, 6, 7, and 8) was still too long, requiring usually from 30 to 40 minutes. Analysis 

 of the data gave rise to the short method described in the revised Examiner's Guide (Part I, 

 p. 192). The order of procedure with the tests there indicated is based upon their separate 

 correlations with total performance scale, and their consequent efficiency in reducing the num- 

 ber of complete examinations. Examination of the 228 records of the earlier Lee investigation 

 showed that the following numbers would have been eliminated from further examination on 

 the basis of the rules which were formulated: The rule excusing those who made 14 or more 

 on digit symbol would eliminate 119 cases ; 22 or more on two tests would eliminate 53 additional ; 

 27 or more on three tests would eliminate 27 additional; 32 or more on four tests would eliminate 

 7 additional. This would leave only 22 subjects to take the complete examination. The time 

 required for giving a performance scale examination was thus reduced to 15 or 20 minutes in 

 the case of a majority of the subjects. 



Camp studies. — In the camps several studies were made touching various aspects of the 

 performance scale. It is possible here merely to indicate the nature of a few of these. 



At Camp Greenleaf, on the basis of 150 examinations a regression equation of mental age 

 upon short performance score was determined as follows: Mental age =0.464 + 77.34 months; 

 or, more roughly, "mental age equals one-half performance scale score plus six years." The 

 150 subjects entering into this investigation ranged in mental age from 5 to 16 years, had been 

 in the United States at least six years, and were all English-speaking. Their performance 

 scale scores showed a correlation of 0.77 with mental age. (Stanfora-Binet and point scale 

 mental ages were thrown together, which probably lowered the correlation somewhat.) 



At Camp Lee an abbreviated performance scale was worked out, composed of cube con- 

 struction (parts (a) and (&)), designs (parts (a), (b), and (c)), and maze (parts (a) and (6)). Raw 

 scores on these tests were used and mental age equivalents determined. The mean deviation 

 of mental ages on this scale from mental ages on the whole scale for 273 cases was found to be 

 0.38 year, and the correlation of mental ages on the two scales, 0.85. 



Numerous correlational studies were reported, but without more definite knowledge than 

 is available regarding the exact nature of the groups on which these were based their meaning 

 is doubtful. 



At Camp Custer a comparison of the results for American and foreign-born subjects was 

 made. The conclusion was reached that foreigners do relatively well in test 2 (manikin and 

 feature profile), test 3 (cube imitation), and test 4 (cube construction) ; but that they are handi- 

 capped in test 7 (digit symbol) and still more in test 10 (picture completion). 



At Greenleaf it was found that the proportion of zero scores in the maze test was reduced 

 from 28 per cent in beta to 2 per cent in the performance scale, and that similarly zero scores 

 in the digit-symbol test were reduced from 49 to 6 per cent. 



