Volume Measures for Linkage Disequilibrium
We discuss the value of volume measures for linkage disequilibrium, showing how they are robust to small sample variation and easily generalized to multi-allelic markers. In particular we introduce Dvol, a volume analogue to D' and show that it performs substantially better when the sample size is small to moderate. Mvol is proposed as a generalization of this measure to multi-allelic markers. Finally a measure based on homozygosity Hvol is suggested as a generalization of R^2. To evaluate these measures, we introduce a sequential importance sampling algorithm. We illustrate their performance on simulated and real data.