Can we establish the effect size that would make detection relatively straightforward? Instead of an absolute criterion for effect size, we can instead establish a relative one: we can compare the effect sizes of loci that contribute to psychiatric disease with those of loci contributing to variation in endophenotypes. Are the latter larger? Our problem is that there are very few robust estimates of the effect sizes for susceptibility loci in either psychiatric disease or endophenotypes. One approach to obtain good estimates is to combine studies using meta-analytical techniques.
