THE CLASSES OF FREQUENCY POLYGONS. 25 



Example of calculating the theoretical curve corre- 

 sponding with observed data. (Fig. 24.) 



Distribution of frequency of glands in the right fore leg of 2000 female 

 swine (integral variates): 



Number of glands 1 2l 3 4 5 6 7 8 9 10 V 

 Frequency 15 20p 365 482 U14 277\ 134 72 22 8 2 



Assume the axis yy' ( Vm) to pass through ordinate 4, then: 

 V V - Vm f f(VVni) f(VVm)* f(VV)* f(V} 



2 2000 998 6148 3872 48568 



v l = 998 -T- 2000 = .499. 



v a = 6148 -*- 2000 = 3.074. 



v, = 3872 -4- 2000 = 1.936. 



> 4 = 48568 -f- 2000 = 24.284. 



Ml = M = 4 .499 = 3.501. 



M 3 = 3.074 ( .499) 2 = 2.824999. 



Ms = - 1.^36 - 3(- .499 X 3.074) + 2(- .499) 3 = 2.417278. 



M 4 = 24.284 -4(-.499x - 1.936) + 6(.249001 X 3.074) - 3(- 499)* = 



_ (2.417278)2 _ 5.843232929 

 Pl ~ (2.S24999) 3 ~ 22.545241683 



24.826297 _ 94. 826297 

 ^ ~ (&824999J* ?.y061935 " 3 ' 110823 - 



F = 6 4- 3 X 0.259178 - 2 X 3.110823 = -f 0.555888 (Type I). 

 6(3.11082 - 0.25918 1) 



.55589 

 21.9857 



= 19.9857. 



d = 1.680774 X .3111 = .5230. 

 d . s= .5230 X 19.9857 = 10.4519. 



b = .840387 4/16 X 20.9857 -f 0.25918 X (21. 9857) 3 = 18.0448. 

 18.0448 - 10.4519 



