xxii Tables for Statisticians and Biometricians [V — VI 



Hence using formula (ii) p. xiii : 

 (- log F) = 25295315 + -31 [14-99573] 



•31 x -9039 ,„„„„ -69 x -5239 AnnnA 



x -43394 



o 



Table V (pp. 12—18) and Table VI (p. 18) 



Probable Errors of Means, Standard Deviations and Coefficients of Variation. 

 (Table V calculated by Winifred Gibson, B.Sc; Table VI by Dr Raymond Pearl 

 and T. Blakeman, M.A. Biometrika, Vol. IV. pp. 385 — 393.) 



If m be a mean, o- a standard deviation and V = lOOo-fin a coefficient of 

 variation, for a population of n, we have 



Probable Error of Mean 



= -G744898fl-/VH = XiO- ( xi ). 



Probable Error of Standard Deviation 



= -6744898o-/V2n = xsff ( xii ). 



Probable Error of the Coefficient of Variation 



= -6744898 F x jl + 2 (-^Yj /V2n (xiii), 



= -6744898/^271 x -f 



-J&x* ( xiv )- 



Table V gives % and ^ 2 for each value of n up to 1000, Table VI gives ■x/r for 

 each value of V proceeding by units from to 50. 



When the frequency n is greater than 1000, the tables may still be used by 

 taking out a square factor, which can be divided out at sight. 



Illustration (i). n = 2834 = 4 x 708-5. 



n = 708, xi = -02535 ; n = 709, *, = -02533. 

 .-. n = 708-5, x ,= 02534, and .'. for n = 2834, 

 we have Xi = "01267. 



Illustration (ii). In the case of the 900 Bavarian crania of the Illustration (iii) 



to Table II the values 



mi = 83-069, a = 3-432, 



