PECCAVIMUS ! 
This papei" is devoted to a number of slips recently made by the Bionietric 
School and which it is desii'able to correct at once, before the formulae which need 
correction pass into general use. Some of these slips are due to war haste, others 
to neglect of terms which ought to have been included in our approximations and 
some to printers' errors. We have to thank Professor Tchoupi-off df Petrograd for 
indicating the existence of sevei'al of these mistakes. 
(I) Biometrika, Vol. XI, p. 215. On the Probable Error of a Coefficient of 
Contingency luitliout Approximation. By Andrew W. Young and Karl Pearson. 
Down to p. 222, equation (xii), this has been again checked without discovery 
of any error. But on that page the authors "take M to be very lai'ge compared 
with N and make = = %;! = %4 = 1 " by an oversight. The values of the ^^'s are 
given on p. 217, ecjuation (vi), and clearly when M is very large compared with N, 
%i — Xi~ Xi^^ '"^^^^^ %'■ 2/N. Accordingly ecpiations (xiii) and (xiv) of p. 222 
for samples from "an infinite population" require modification and should be*: 
(xiii). 
- (2 - 40-) c - 16(^- + 10<^^ - 2 
- >S (2c - 4(^- + 8) - 6(^^ + 1 24>' + 4>c(j>' - c-^ - 2c + 2 
(xiv). 
* The changes due to xa affect the term in but the original (xiii) lias a wrong sign to the third 
term in IjN^. 
