A methodological model to study the effects of toxins on child development.

Human research on the effects of drugs, medications, pollutants, and other toxins on fetal and child development requires longitudinal studies. Such studies must recognize the heterogeneity of populations and individuals, the multiplicity of variables, and the dynamic interactional character of development. This requires the construction of an a priori theoretical model, selection of research tools to fit the model, and the use of appropriate multidimensional data analysis techniques that can identify profiles of variables in individuals and subgroups, and can trace development over time. A model, based upon the facet theory of Louis Guttman, is presented with examples from a study of infant offspring of methadone-maintained women. An introductory explanation of one non-metric multidimensional data analysis technique. Guttman's Multidimensional Scalogram Analysis (MSA), is presented. Examples of its use and its relation to the theoretical model are given in subsequent papers.