Properties of the major gene index for three-allele and two-locus models

The expected value of the MGI(2) statistic was evaluated for several three-allele and two-locus models for which we have specified dominance relationships among phenotype classes based on heterozygote and homozygote genotype groupings. In a parallel simulation study we investigated the nature of MGI(alpha) for alpha = 1/2, 1, 2 under more elaborate continuous trait expressions incurred from superposition of a background distribution upon each of the phenotypic mean effects.