Using these approaches, we intend to balance the competing factors affecting power: sample size and purity of assessments. Analyses of the first class of subjects are designed to most closely match the original report of [15]. By examining the more severe stressor, childhood maltreatment, in a larger sample with no age restriction, our goal is to potentially increase our ability to see the influence of 5-HTTLPR variation if the effect is not limited young adulthood. Our broadest analysis, with stress broadly defined in the largest population, can be expected to maximize power if there is a general effect of 5-HTTLPR variation moderating the impact of stress exposure on depression. If we do not see the influence of 5-HTTLPR variation in this final set of analyses, but it was present in at least one of the previous analyses, we will be able to examine which factors reduce the effect of the association. An important benefit of this design is that we will also examine the degree to which results observed with narrower analyses generalize to the broader analyses, which provides the opportunity to clarify the importance of specific phenotype, stressor, and age requirements.
