644 MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



The equations as determined from these correlation coefficients are: 

 tf=Jfc + 2 o O.7O6740A 





0.5076(^A + 0.42 1(/^) | 



O.44O30- 4 ) + O.25650A + O.2789(-^)l 



0.3963('^- 4 ") + 0.1978('^ + 0.1997('^ e Vo.2468('^ 7 ')| 



[Vol. XV, 



(13) 

 (14) 

 (15) 

 (16) 



and the total correlations and standard deviations of class interval subgroups are: 



Equation (13) i? = 0.7067 Standard deviation 57.33 



(14) .8219 46.21 



(15) .8636 40.89 



(16) .8841 37.91 



In the same manner as the class-interval subgroups of the distribution of alpha total 

 scores were redistributed upon the combination scale, we redistribute the class-interval sub- 

 groups for the beta total score by means of table 162, which is calculated from the equations 

 and standard deviations given above. 



Table 162. — Shotting how the frequencies of each class interval of a beta distribution should be disposed on the combined 



scale. 



It will be noted that in table 161 beta 7 is omitted from the combination of variables, 

 which is taken as typical of the highest four class intervals. This omission is because of the 

 limitation of the upper end of the beta 7 scale, which we may consider acute enough to render 

 scores of 9 and 10 differentially of little significance and of the same character as zero scores in 

 so far as they are, owing to inadequacies of the test, substitutes for scores of 11, 12, 13, etc. 



Finally, we find the correlation of Stanford-Binet mental age with combination scale scores 

 to be 0.8871, which enables us to write the following regression equation, giving probable com- 

 bination scores for given mental age: 



0=1.01 M. A. + 0.33 



Since we adopted the policy of distributing the class-interval subgroups of alpha and beta total 

 score distributions, where variability was not constant throughout the range, we may follow 



