Final answer:
The MYCIN system used computer-based decision aids based on the Bayesian probability theory.
Step-by-step explanation:
The early clinical decision support system that used computer-based decision aids based on the Bayesian probability theory is the MYCIN system. Developed in the early 1970s, MYCIN was created to diagnose bacterial infections and recommend antibiotics.
It utilized a set of rules and the Bayesian inference method to assess the likelihood of various diseases given specific symptoms and patient data. Although initially used for that narrow area of medicine, its decision-making processes and theoretical underpinnings were influential in the development of other clinical and non-clinical expert systems.