differential diagnosis(A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or [witha double delta symbol]) is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible (and the process may be termed differential diagnostic procedure), and may also refer to any of the included candidate alternatives (which may also be termed candidate condition). This method is essentially a process of elimination or at least of obtaining information that shrinks the "probabilities" of candidate conditions to negligible levels. The "probabilities" at issue are epistemic rather than ontological in that they are imaginative parameters in the mind of the diagnostician (or, for computerized or computer-assisted diagnosis, the software of the system), while in reality the target (such as a patient) either has a condition or not with an actual probability of either 0 or 100%. Differential diagnostic procedures are used by physicians, psychiatrists, and other trained medical professionals to diagnose the specific disease in a patient, or, at least, to eliminate any imminently life-threatening conditions. WK Alexander Demidov)
