Accuracies of imputed genotypes in 59,000 SNPs (y axis) versus a summary of the LD patterns surrounding them (x axis). The summary of LD is a weighted average of the pairwise D' between each SNP to be imputed and all other SNPs in the same chromosome with weights that are calculated as . In the formula, di is the physical distance between the SNP to be imputed and the ith SNP, in 100 kb, and di' is the estimate of LD between the same two SNPs.
Zhao et al. BMC Genetics 2008 9:85 doi:10.1186/1471-2156-9-85