APPRECIATION OF INTELLIGENCE ^3 



a method which has not commended itself to statisticians, 

 and which grossly exaggerated even the results which flow 

 from such defective data.^ The staff of the Eugenics 

 Laboratory never goes out of its way to attack other 

 people's work ; it states its own conclusions and the evidence 

 on which they are based, but it feels bound occasionally to 

 reply to innumerable critics, who, if they have done any 

 work at all, in nine cases out of ten have done it on a still 

 more ' dubious foundation ' to which they have never even 

 applied their own canons of criticism. 



Mr. Yule has repeated in this case precisely the type of 

 criticism he made once before in attacking qualitative cate- 

 gories. He has asked why other things had not been done ; 

 which either could not be done or had been done. In this 

 particular case, place in class or examination was not avail- 

 able — we knew it, however, to be very highly correlated 

 with the category actually used. It is reasonable to suppose 

 that Mr. Yule was unaware of this correlation, but this does 

 not justify him in sweeping condemnation of the Eugenics 

 Laboratory and its investigations, investigations which are 

 often based on the general drift of work in progress fully 

 known to the members of the staff, but not yet ripe for 

 publication. 



The memoir on the Influence of Defective Physique and 

 Unfavourable Home Environment on the Intelligence of 

 School Children was issued, as it states in its opening 

 words, with two very definite purposes : ' (a) to illustrate 

 the difficulties which arise in attempting to make reliable 

 and comparable observations on school children, and (b) to 

 indicate the difficulties met with in the statistical treatment 



1 The associations found by Mr. Yule from the census returns for ' blindness ', 

 imbecility, and deaf-mutism are equally fallacious, or rather more so. Thus 

 the association of deaf-mutism and mental defect for the census of 1901 gave 

 by Mr. Yule's process .82, while by fourfold correlation process it is '27 ! 



c 



