Models and inference methods for clinical systems: a principled approach.

Previous papers have argued for the existence of three different models in many clinical information systems--for the medical record, for inference in guidelines, and for concepts and re-usable facts. This paper presents a principled approach to deciding which information belongs in each model based on the nature of the queries or inference to be performed: necessary or contingent, open or closed world, algorithmic vs heuristic. It then discusses an important class of systems--"ontologically indexed knowledge bases"--and issues of metadata within this framework.