Skip to main content
. Author manuscript; available in PMC: 2015 Dec 1.
Published in final edited form as: Psychophysiology. 2014 Dec;51(12):1225–1245. doi: 10.1111/psyp.12344

Figure 6.

Figure 6

Q-Q plot for SNP associations with total power at Cz. The 45° line gives the expected value under the null distribution. The area shaded in gray corresponds to the 95% acceptance region. Median and mean genomic control values are given in the inset in the upper left. N refers to the number of SNPs, which is 8 fewer than the number of SNPs on the array because there was no variation for 8 SNPs in this sample. Q-Q plots in GWAS give the observed p-values against the expected p-values under the null distribution of no association, although the additive inverse of the common log of p-values (−log10[p]) is used in order to emphasize small p-values. Because the vast majority of SNPs are not expected to be associated with a given phenotype, observed p-values should conform closely to their expected values, falling on or very close to the 45° line. The gray region in each plot depicts the 95% confidence region (null acceptance region).