2. Despite the impressive mathematical demonstration of nonbias, I suggest there are a few potential areas of bias. First, Dr. Faraone included one of his own studies in the meta-analysis. Second, I can hardly imagine more biased groups to cull data from than "colleagues presenting such data at national meetings" and "the molecular genetics e-mail network" (1, p. 1053). Also, the authors stated, "Unfortunately, neither type of study has consistently confirmed the putative association between ADHD and the DRD4 7-repeat allele" (p. 1052). Unfortunate for whom?