The certainty factors are based on the concept that at any given time their is a Certainty Factor associated with any given priori hypothesis about the problem at hand. The current measure of belief and the current measure of disbelief. These measures range from 0-1. The relationship between evidence and and the hypothesis is expressed in terms of rules. Each rule is associated with a tally factor. which represents the innate credulity of the rule itself.
People can relate to the increase in certainty due to increase in evidence.
Always choose the system which is appropriate to the job at hand. Select the knowledge representation and uncertainty management and inference technique which is needed for the level of problem solving concerned. A model is a simulation of a real system, a description of some process. It simplifies and abstracts some aspect of the total systems behavior. Output of models have to be compared with the business policy of the company.