GeNIe Tutorials: Tutorial 7 - Entering and retracting evidence
From DSL
Objective of the tutorial: To learn how to set and clear evidences for nodes in the network.
Estimated Time: 10 Minutes
At the end of the tutorial you will be able to:
- Set and clear evidence for each individual node.
- Clear evidence for the entire network using one command.
Entering observations (evidence) is one of the basic operations on a probabilistic model. It amounts to adjusting the model to a new situation, one in which more information is available. It allows to query the system subsequently about the new, posterior probability distributions. If you have gone through Tutorial 3 - Building a Bayesian Network, you might remember that you have already entered evidence for the Expert Forecast node. Let us go through it again.
You may load the model created in Tutorial 3 - Building a Bayesian Network from the 'Example Networks' folder. It is names tutorial3.xdsl.
To enter evidence into your model, right-click on the node in question (in the picture below, node Expert Forecast) and choose Set Evidence.
Alternatively, select the node in question and choose Set Evidence submenu from the Node menu.
To retract evidence, right-click on the node with previously entered evidence (in the picture below, node Forecast) and choose Clear evidence.
Alternatively, select the node in question and choose Clear evidence from the Node menu.
You can also retract all evidence by choosing Clear all evidence from the Network menu:
To enter different evidence instead of retracting evidence altogether, just set different evidence from the Set Evidence sub menu.
This concludes your tutorial on Entering and Retracting evidence.
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