Chunk #93 — 7.0 Recommendations to Advance Endophenotype Genetics — 7.3 Adequate power to detect individual effects is crucial but almost never attained in existing endophenotype genetic association studies — 7.3.1. Power and sampling schemes in GWAS
The reason we include power calculations under “special” circumstances in the right-hand side of Table 3 is not because we believe that it is easy or realistic to cut measurement error in half or increase variant MAF to 50%. In fact, we have argued throughout this article that the failure to find genetic variants associated with electrophysiological candidate endophenotypes is unlikely to be due to their operational definitions or the precision with which they are measured, and it is clear that phenotypic selection schemes will not result in great MAF enrichment given how small the associations between genotype and phenotype are. The purpose of Table 3, instead, is to respond directly to the argument that some particular study sample is special and therefore extremely powerful. To create a caricature of the argument: a small study has huge statistical power because it used the best and most expensive measures collected in-person over the course of days in multiple waves on a very special sample of phenotypically extreme individuals from a population that is very hard to access and has not been
