In the context of Target Mean Analysis (Validation Mode: Analysis | Visual | Target Mean Analysis), what does it mean to "Use Hard Evidence"?
The example below illustrates the difference between using Hard Evidence (box checked) and using Soft Evidence (box unchecked):
If Soft Evidence is selected (Hard Evidence unchecked), two kinds of evidence are used:
- Hard evidence, for the extreme values (the min and the max),
- Soft evidence (by setting target mean values) for the intermediate points.
Let n be the number of states of the node under analysis.
n+1 reference values are defined by using the values of the n states plus the expected value given the current marginal probability distribution of the variable.
These reference values define n intervals where intermediates points are equally distributed. By default, the number of intermediate points is three, but this value can be changed via the Settings (Options | Settings | Analysis | Target Mean Analysis).