However, if heterogeneity exists, then this association may not be possible to extend equally well to diverse populations. In the presence of considerable heterogeneity, if random effects calculations are used, no meta-analysis, no matter how large would have enough power to detect an association at genome-wide significance [28]. Moreover, the discovery process in the GWA setting is such that for discovered associations, on average, the observed heterogeneity may be less than the true heterogeneity: those associations that happen to have more observed heterogeneity in the data get more inflated confidence intervals by random effects calculations and are less likely to pass the threshold of genome-wide significance; while those that by chance have no or less heterogeneity than their true heterogeneity are more likely to be considered replicated. This makes interpretation of homogeneity particularly difficult.
