I was writing something about GWAS, however is not really my field and so lot of reading. I encountered this statement in Bush and Moore, 2012 (Chapter 11: Genome-Wide Association Studies, 2012):
There are two primary classes of phenotypes: categorical (often binary case/control) or quantitative. From the statistical perspective, quantitative traits are preferred because they improve power to detect a genetic effect, and often have a more interpretable outcome. For some disease traits of interest, quantitative disease risk factors have already been identified.
Can anyone help me to understand why quantitative trait has more power (even with some formulas it will be great)? are they referring to QTL somehow?
Thank you very much