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I am interested in obtaining the variance for measures of association in 2 x 2 tables. In particular, for a table with entries a, b, c, d, V = (ad - bc) /sqrt((a+b)(a+c)(b+d)(c+d)) is a well-used measure (known as delta by geneticts looking at linkage disequlibrium). Kendall and Stuart (vol 2, 1974 edition) give a formula for var(V), but it is not symmetric in b and c, which seems counter-intuitive. I am unable to derive it myself or find another source of the formula. Any pointers would be much appreciated. Cathryn Lewis %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%