396 



Mr. W. F. Sheppard on the 



Calculated, p=10 .. 

 Calculated, 7> = 20 .. 

 True value 



•545 529 242 -119 0fi5 036 



•545 539 246 



•119 053 606 



007 406 699 



007 400 460 



007 400 082 



Calculated, p = 10 022 282 814 -003 116 676 



•545 539 924 j -119 052 858 



+ 



Calculated, » = 20 

 True value 



•022 275 637 -003 112 401 

 022 275 201 003 112 161 



Example IT. 



Z=xX-f + l(l-X)-i 



A. 



X. 



A. 





X. 









•ooo 



000 



000 



•6 



■697 



374 



666 





1 



•ooo 



063 



969 



•7 



•886 



710 



165 





2 



004 



034 



329 



■8 



•975 



442 



372 





3 



•041 



904 



6-13 



•9 



•998 



408 



477 





4 



•180 



187 



494 



10 



1-000 



000 



000 



5 



•430 



159 



709 











M t . 



+ 



Calculated, _p= 10...., -471 428 582 , T71 772 175 

 True value ! "471 428 571 ' "171 772 196 



+ 



•006 813 411 

 006 813 360 



M4- V-s- 



+ + 



Calculated,^ = 10 j -037 605 033 | -003 280 297 



True value 



•037 605 134 j -003 280 



L23 



5. Various difficulties may arise in applying the method ; 

 but they will usually be due to imperfections in the original 

 observations, rather than to defects in the method itself. The 

 following special points may be noted : — 



(i.) When the observations are very accurate, but few in 

 number, there may be large gaps between successive values 

 of X; and there may thus be a doubt as to the exact value to 

 be assigned to any particular centile. But the doubt will 

 only occur, in general, near the centre of the range ; and the 

 inaccuracy in M 1 will be subordinate to its " probable error," 

 while the inaccttracy in fi 2 , fi 3 , . . . will be very small. 



