purposes of genetical analysis must therefore be reached by empirical means. Obviously it should be one which facilitates both the analysis of the data and the interpretation and use of the resulting statistics…The scale should preferably be one on which…the interactions among the genes and between genotype and environment are absent, or at any rate as small as they can reasonably be made.” (p. 64, our italics). Lack of careful attention to this goal leaves in question the heuristic value of claims to find G × E in psychiatric data.
