230 Or the Probable Error of a Coefficient of Contingency 
and (C) to 
'V-^,{^^-^'^> + ^(-i)} 
where c is the number of cells in the table and H is the harmonic mean of the cell 
contents. 
Rou»h approximations in the case of zero contingency are given by 
and a-,^.: = > 
and from these we can derive as a rough upper limit to the value of cjy^ given by a 
random sample from a population of zero contingency 
c ^V2c c /, 2-8284\ 
