Nine-cell diagnostic decision matrix. A model of the diagnostic process; a framework for evaluating diagnostic protocols.

A nine-cell diagnostic decision matrix is described. This matrix can be viewed dynamically as a model of the diagnostic process. The matrix provides for display of equivocal test results and test results of patients who have ill-defined or incompletely determined disease. The matrix represents an improved model for evaluating diagnostic test protocols. Diagnostic test characteristics related to this model are described. Potential advantages and uses of the model are discussed; among them are possibilities for development of improved diagnostic protocols and improved definitions of disease.