Allelic correlation
= Allelic correlation
{title2=$r^2=D^2/[p_A(1-p_A)p_B(1-p_B)]$}
For two segregating biallelic loci, encode the allele on a random population <haplotype> by indicator variables $X,Y$. Their <covariance> is the <linkage disequilibrium> coefficient $D$. The squared <correlation> is $r^2=D^2/[p_A(1-p_A)p_B(1-p_B)]$, between zero and one. It measures how well one marker predicts the other and is undefined if either marker is monomorphic.
// Target: biology.bigb