Table 2. Studies that published estimates of the X-chromosomal and autosomal admixture fractions of an African-American population.

	Mean ancestry estimates (%)
Reference	African autosome $\left(E\left[H_{1,g}^{\mathrm{A}}\right]\right)$	European autosome $\left(E\left[H_{2,g}^{\mathrm{A}}\right]\right)$	African X chromosome $\left(E\left[H_{1,g}^{\mathrm{X}}\right]\right)$	European X chromosome $\left(E\left[H_{2,g}^{\mathrm{X}}\right]\right)$	% female
Cheng et al. (2009)	80.7	19.3	84.5	15.5	55.7
Bryc et al. (2015)	73.2	24.0	76.9	19.8	52.3
Bryc et al. (2010a)	77	23	81	19	66.3
Lind et al. (2007)	80	20	87.9	12.1	0
Tian et al. (2006)	81.8	18.2	87.1	12.9	Not reported

As the X chromosomes of females and males were considered jointly in the studies, we list the fraction of the sample that was female. In each study, the X chromosome shows elevated African ancestry compared to the autosomes. Values were compiled from quantities reported in the studies or by taking 1 minus an African estimate (“population 1”) to obtain a European estimate (“population 2”) or vice versa, with the following exceptions: For Bryc et al. (2015), the “autosome” estimates are genome-wide, including the X chromosome; the percentage of females was kindly provided by K. Bryc (personal communication). For Bryc et al. (2010a), we obtained an African X-chromosomal estimate by visual inspection of their figure 4g, and we counted the number of females from their supplementary material. For Tian et al. (2006), we computed the values from information reported in their figure 5 legend.