Figure 3 also shows that non-Gambian panels can improve imputation accuracy in the presence of a Gambian panel: the orange curve represents the addition of haplotypes from a moderately diverged population (GHN) and the black curve represents the further addition of a worldwide reference panel (HM3). These results support our strategy of using cosmopolitan reference panels: regardless of which reference data are available, the highest accuracy is achieved when using all available haplotypes and letting the imputation method decide which ones to use.
