CFa=60% CFb=80%
CFa=60% CFb=80%
IF a OR b
CFa=60% CFb=80%
CFa=60% from 2nd source
70+(60/100)x(100-70)
Then c=5 with 80% confidence
(premise CF=90%)
| Example | Method | Result | Justification |
|---|---|---|---|
| IF a AND b CFa=60% CFb=80% | Minimum | Premise is true, CF=60% | Both a and b must be true for the premise to be true: the overall certainty is driven by the weakest certainty. |
| IF a OR b CFa=60% CFb=80% | Maximum | Premise is true, CF=80% | The premise is true if either a or b is true: the overall certainty is driven by the strongest certainty. |
| IF a AND b IF a OR b CFa=60% CFb=80% | Average | Premise is true, CF=70% | A compromise between the Maximum and Minimum methods for either premise. |
| CFa=70% from 1st source CFa=60% from 2nd source | Probability Sum | Final CFa=88% 70+(60/100)x(100-70) |
30% uncertainty remains from the first certainty factor of 70%. The second CF explains 60% of this remaining 30%. (Note: applying the two certainty values in reverse order yields the same result.)
|
| IF a AND b Then c=5 with 80% confidence (premise CF=90%) | Multiplication | c is 5 with 72% confidence | The confidence assigned to the attribute in the rule conclusion is assumed independent of the premise confidence level, so the two are combined by multiplying as independent probabilities would be combined. |