Ixx 



Tables for Statisticians and Biometricians [VIII IX 



Illustration (ix). Mothers Habits and Baby's Health. 



Mother's Habits 



Here 

 and thus 

 while 



4(1 -a h ) = -298,734, (1 -a k ) = -288,608, 

 h = -52805, k ='55746, 



d/N = 114,7679, 

 6> = -2805, < = -7195, % = '5746, ^ = -4254. 



Between h= "50 and "60, and k = "50 and '60, the above value of d/N occurs in 

 tables of r for -20, '25 and -30, but not in those for r = *15 and *35. We therefore 

 start by interpolating into "25. Using formula (a) 



*i - - 3060 ' 7530 (SSJ + ' 4134 ' 2470 



i i QS 94*n f- 115 ' 238 ) ..-.fin ^on f'104,390) 

 1193,2470 . 108878 + 1611,7530 . 098302 [ - 



The first or upper series of numbers gives us d/N = "117,2044, or too high a value. 

 Hence the second system is inserted for r = '20. This gives djN= '110,7964, and 

 by linear interpolation, 



The true value is -2317. 



We now examine this result by aid of formula (/3). The S 2 's and S /2 's are as follows : 



S 2 2 0> o = 6% 



Hence 



r=-20 



-000,337 

 -000,284 

 -000,445 

 -000,383 



r=-25 



-000,278 

 -000,227 

 -000,395 

 -000,333 



= - -0336,3662 < 5 > 



4254 





5746 



000,284 



.. Wd.fi -7iQ^ . J'000,383 



5746 (^ 7195 j^^j + 280, j. 



= -000,0814 for r = '20, and =--000,0694 for r = -25. 



