Abstract: | A simple random sample is observed from a population with a large number‘K’ of alleles, to test for random mating. Of n couples, nijkl have female genotype ij and male genotype kl (i, j, k, l{1,…, A‘}). The large contingency table is collapsed into three counts, n0, n1 and n2 where np is the number of couples with s alleles in common (s = 0,1, 2). The counts are estimated by np?o where n0, is the estimated probability of a couple having s alleles in common under the hypothesis of random mating. The usual chi-square goodness of fit statistic X2 compares observed (ns) with expected (np?) over the three categories, s = 0,1,2. An empirical observation has suggested that X2 is close to having a chi-square distribution with two degrees of freedom (X) despite a large number of parameters implicitly estimated in e. This paper gives two theorems which show that x is indeed the approximate distribution of X2 for large n and K1“, provided that no allele type over-dominates the others. |