Think Tank participants discussed several challenges unique to performing replication in studies of GxE. One challenge is determining what aspects of the GxE interplay are factored into replication. As discussed above, often the goal of GxE studies is to model the joint effects [Weinberg 2012b]; therefore, such joint effects should be the focus of replication. However, the best approach to test if the joint effects are similar across studies is not as straight forward as when considering a single interaction term. Moreover, without similar patterns of joint effects, replication of the interaction coefficient is not interpretable [Mechanic, et al. 2012].
