Figure 3. Quantile-quantile plots of the age-related eye disease study (AREDS) genome-wide association study (GWAS). A: Scatter plot of the −log10 (p values) expected under the null hypothesis of no genetic association versus the observed −log10 (p values) are shown for all subjects. B: This is a scatter plot as in A, but for white subjects only. C: This is a scatter plot of white subjects corrected for population stratification using principal components methods without exclusion of known loci. D: This is a scatter plot of white subjects corrected for population stratification using principal components methods with exclusion of known loci. A–C: These plots show that correction for population stratification reduced the genomic inflation factor from 1.23 to 1.01. D: This plot suggests that there is evidence for additional single nucleotide polymorphisms (SNPs) contributing to age-related macular degeneration (AMD) after statistically accounting for known loci.