We also compared the frequency of SNPs in the self-reported European and African American groups. First the SNPs were sorted by the percentage of heterozygotes present in the European American individuals. Then we took the squared difference of the allele frequency of each group for each SNP in both the Illumina and Affymetrix datasets; this value is considered a measure of information content for each SNP. By this measure, a SNP that is fixed for one allele in European Americans and the other allele in African Americans would have an information content of 1.
