Mycin

From Free net encyclopedia

Mycin was an expert system developed over 5 or six years in the early 1970s at the Stanford University, written in Lisp, by Edward Shortliffe under Bruce Buchanan and others; it derived from Dendral, but considerably modified it. The system was designed to diagnose infectious blood diseases and recommend antibiotics, with the dosage adjusted for patient's body weight — the name derived from the antibiotics themselves, as many have the suffix "-mycin".

Mycin operated using a fairly simple inference engine, and a knowledge base of ~500 rules. It worked by querying the physician through a long series of simple yes/no or textual questions, at the end of which, it provided a list of possible culprit bacteria, its confidence in each diagnosis, the reasoning (referring to individual questions and answers) behind each diagnosis, and its recommended course of drug treatment.

In fact, Mycin was never actually used in practice. This wasn't because of any weakness in its performance — in tests it outperformed members of the Stanford medical school. It was as much because of ethical and legal issues related to the use of computers in medicine — if it gives the wrong diagnosis, who can be held responsible? Issues with whether human experts would find it acceptable to use arose as well.

A difficulty that arose during the writing of this and subsequent expert systems has been the extraction of the knowledge from human experts into the rules, the so-called knowledge engineering.

Research conducted at the Stanford Medical School found MYCIN to have a correct diagnosis rate of about 65%, which was better than most physicians who were not specialists in diagnosing bacterial infections, and only slightly worse than those physicians who were themselves experts in the field (average correct diagnosis rate of about 80%).

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