XVII] 



(3) Houses in course of erection in 

 Urban and Rural Districts. 



Introduction xxxv 



(4) Imbecility and Deaf-Mutism. 



(5) Developmental Defects and Dullness. 



<" the menn square contingency = \*JN and <f> is the product-moment coefficient 

 on the assumption that the 'presence of the character' is to be considered as 

 a concrete unit*. The coefficient of mean square contingency C' = V</> 2 /(! + $ 2 ). 



The following table gives the values of %*, <-, <f> and C it and the values of P 

 deduced. 



For example, from Table XVII by Formula (i) we have for %*= 133-3265: 



(- ,o g ,, , *. + [,0-770] - 5 () (") 



log P - 28'015, 

 P = 1 '035/1 O a . 



= 27-985, 

 and therefore 



which leads to 



Or again, for x '= 8014'62 : 



- * I- .73,,. 

 = 1738-498, 



* Pearson and Heron, Biometrika, Vol. ix. p. 107. 



,000] 



9 



