878 



SCIENCE 



[N. S. Vol. XXXIX. No. 1015 



rives complicated formulas which we have 

 used in calculating our data. Pearson himself 



felt that he had solved an important question, 

 for he said: 



AVERAGE DIFFERENTIAL ABILITIES OF PUPILS CHOSEN AT RAND0M2* 



24 For practical use this table should be consider- 

 ably extended. 



25 The marks for a class of 100 are adapted 

 from the tables of H. L. Moore's "Laws of 



Wages," New York, 1911, pp. 98, 99. Moore com- 

 puted his table to six decimals. He applies Pear- 

 son 's statistical theory to the study of ' ' wages and 

 ability. ' ' 



