One of these things is not like the others: the idea of precedence in health technology assessment and coverage decisions.

Health plans often deliberate covering technologies with challenging purposes, effects, or costs. They must integrate quantitative evidence (e.g., how well a technology works) with qualitative, normative assessments (e.g., whether it works well enough for a worthwhile purpose). Arguments from analogy and precedent help integrate these criteria and establish standards for their policy application. Examples of arguments are described for three technologies (ICSI, genetic tests, and Viagra). Drawing lessons from law, ethics, philosophy, and the social sciences, a framework is developed for case-based evaluation of new technologies. The decision-making cycle includes (1) taking stock of past decisions and formulating precedents, (2) deciding new cases, and (3) assimilating decisions into the case history and evaluation framework. Each stage requires distinctive decision maker roles, information, and methods.