\ \ \ I \ 



for Stnllsl iriims it ml /iiimii'tn'i-iiiiix XVII 



TABLE XVII (,, :ih 



\'n I ties of (/(//' i <-<irrc/>iiiidiny to given values of %* in a fourfold l<ilil>: 

 (K. Pearson: On a Novel Method of regarding the Association of two Van 

 classed solely in Alternate Categories. Drapers' (\niijmny Research Memoirs, 

 Biometric Series, vm. Dulau & Co.) 



If individuals be classed by the characters into -1 :md not-^1, B and not-.fi, we 

 form a tetrachoric table of the form 



For such a table : 



N(ab-cdY 



(a + b)(c+d)(b 



.(xxxi), 



gives a measure of the probability of independence, and, if the two attributes are 

 highly associated, will De large and P the probability of independence very 

 small and largely outside Palin Elderton's Table XII. Table XVII provides for 

 such cases. 



Illustrations. The following tables are given by Mr G. U. Yule in his Theory 

 of Statistics*. His conclusions with regard to them arc: 



1. Datura : " No Association." 



2. Eye Colour in Father and Son : " Shows the tendency to resemblance." 



.3. Houses in course of erection, Urban and Rural : " Distinct Positive 

 Association." 



4. Imbecility and Deaf-Mutism : " High Degree of Association." 



5. Developmental Defects and Dullness : " Very high indeed." 



It is required to measure the degree of probability that the variates in these 

 five cases are independent. 



(1) Datura. (2) Eye-Colour in Father and Son. 



Colour of Flower. Father. 



* Pp. 37, 34, 62, 33, 84 and 45 respectively. 



