A vital question regarding the use of any new DSM assessment of TD, concerns how the scale score (criteria or item endorsement) is translated into a categorical appraisal of dependence (e.g., 0—1= not dependent, 2–4 = dependent; > 4 = severe dependence). It is currently unclear what sort of dependence metric is optimal for TD (see [10]). Presumably empirically driven strategies should be used to generate appropriate cut-scores (e.g., decision tree models, ROC curve methods; e.g., [117]). In addition, a dimensional and continuous metric could be developed for diagnosis, although some research [17] suggests that dependence may be taxonic (possessing features of a discrete category). The criteria and research methods we have outlined would be appropriate for the development of either a dimensional or quasi-continuous scoring system, or for a continuous scoring system for research and a categorical system for clinical use [118].
