Although current theoretical and empirical estimates of future success are fraught with uncertainty, it is possible to use traits where large meta-analyses have already been performed to try to predict outcomes for GWA meta-analyses of traits and diseases where the sample size has not yet increased as rapidly. Such an analysis may be a useful guide for deciding whether to put new resources into increasing sample size. In two empirical attempts to catalogue the relationship between increasing sample size and number of loci discovered across multiple traits (48, 93), it appears that, once some loci have been discovered, the number of loci tends to increase more or less linearly with sample size.
