Approximately three-quarters of the alcohol-related GxE studies did not detect one or more GxE effects that they reported testing, and it is likely that some unknown proportion of published results represent false positives (Type I error). In many published reports it is unclear how many different combinations of genotypes, environmental risk factors, and outcomes have been analyzed without correcting for multiple testing. Additionally, statistical interactions are sensitive to scaling: different measurement scales can give different answers and non-linear transformations can eliminate (or create) evidence for GxE (Eaves, 2006). This is particularly problematic for alcohol-related GxE studies given the large number of potential interactions tested, lack of sufficient information on why variables were scaled certain ways, and the ensuing high probability of false positives.
