(2009) found that stressful life events moderated additive genetic, shared environmental, and unique environmental influences on externalizing behavior (including alcohol use), which is similar to our findings with the transformed variable. Although both the raw and transformed results are consistent with previous findings, the change from trend to statistical significance of these results across transformations within the Finnish sample provides a useful example of the potential effect of heteroscedasticity on GxE effects. Heteroscedasticity can produce biased standard errors. Transforming the alcohol use variable reduces the heteroscedasticity leading to unbiased standard errors and a significant GxE finding in the transformed (but not raw) alcohol use variable. In addition, although similar events may have been assessed in each of these studies, the extent to which they were perceived to be stressful was not included in these analyses (i.e., the events measured in this study are potentially stressful life events). These factors may partially explain some of the ambiguity in the nature of the GxE relationship for adolescent alcohol use and potentially stressful life events.
