no. 3.] PSYCHOLOGICAL EXAMINING IN THE UNITED STATES AKMY. 635 



Table 156. — Showing the means and standard deviations used in this study and how they were obtained — Continued. 



The mental age distribution was treated in the same way as beta test 6. Since there is 

 no piling up of cases in the extreme class intervals, the mean and standard deviations were 

 taken at their face value. They are: Mean, 53.6912 (in quarter years); standard deviations, 

 11.3848. 



The means for the alpha total, beta total, and combined scale distributions were obtained 

 by summing the means of the component tests. The standard deviations for the totals, alpha 

 and beta, and the combined scale were calculated from the standard deviations of the com- 

 ponent tests and from the intercorrelations by the formula given in Yule's Theory of Statistics, 

 page 211. These means and standard deviations are listed in the table below. 



From the set of correlation coefficients, standard deviations, and means thus obtained 

 it is possible to form multiple regression equations connecting any set of variables we choose, 

 and therefore values can be obtained to substitute for all zero scores. A rating on the com- 

 bination scale denned above can therefore be obtained for every individual in our experimental 

 sample, and the distribution of these ratings should give us a much more nearly correct picture 

 of the distribution of intelligence than does the distribution to total beta scores, or total alpha 

 scores, or of Stanford-Binet mental ages. Similarly, in the case of individuals who have had 



