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Set as Target Node

Set as Target Node

Context

  • In BayesiaLab, Supervised Learning includes a set of algorithms that can learn Bayesian networks that have a structure entirely focused on characterizing a Target Node.
  • In other words, the Target Node is the equivalent of what would be considered a dependent variable in traditional modeling approaches.
  • The Target Node is visually distinguished from a normal node by its "bullseye" styling .
  • Additionally, the Monitor that corresponds to the Target Node features a green background.

With Unsupervised Structural Learning, having a Target Node in the network has no influence on the learning algorithm.

Usage

  • There are several ways of defining a node as a Target Node:

In the Modeling Mode F4

  • You can define a node as a Target Node by right-clicking on it and selecting Set as Target Node from the Node Context Menu.
  • Selecting the same item again from the menu reverts the node to its original role.
  • Holding T and double-clicking on a node turns it into a Target Node. Holding T and double-clicking on a Target Node makes it a normal node again.

In the Validation Mode F5

  • You can define a node as a Target Node by right-clicking on it and selecting Set as Target Node from the Node Contextual Menu.
  • You then have to choose the Target State from the drop-down list.
  • Holding T and double-clicking on a node also turns it into a Target Node.
  • You can also define the target via Monitor:
    • Bring up the Monitor of the desired node in the Monitor Panel.
    • Then, while holding T, double-click into the bar chart area of that Monitor.
    • This sets the Target Node and the Target State at the same time.
⚠️

If there is already a Target Node in the network, assigning a new Target Node automatically reverts the previous Target Node to its default status. At any given time, there can only be one Target Node in a network.

Target State

  • Whenever you have a Target Node, there is automatically a Target State.
  • By default, the first state of a node is set as the Target State of a Target Node.
  • This Target State is marked with a bullseye symbol on the Monitor of the Target Node.
  • While a Target State is present whenever there is a Target Node, the Target State does not affect the learning algorithms in any way.
  • As such, you can disregard the Target State for all modeling purposes.
  • In fact, the Target State is neither visible nor accessible in Modeling Mode F4.
  • However, for some analysis purposes in the Validation Mode F5, it can be useful to consider a Target State.
  • For instance, a Target State can be used for evaluating a model with regard to predicting one particular state.
  • In many applications, only one particular state is of relevance. For example, a Target Node may represent multiple virus types, e.g., Dengue, Zika, Rhinovirus, Influenza, and Coronavirus but, perhaps, only the model's performance for diagnosing the Target State Coronavirus is critical.
⚠️

For structural learning, it is important which node is the Target Node but it does not matter what the Target State of the Target Node is.

Usage

  • Given that it is irrelevant for modeling purposes, the Target State is only visible and modifiable in Validation Mode F5.
  • In Validation Mode F5, there are multiple ways you can set the Target State to the state of interest:

For an Existing Target Node:

  • Option 1:
    • Right-click on the Target Node and select Set as Target Node from the Node Context Menu again.
    • This brings up a Target Selection window, from which you can choose the Target State.
  • Option 2:
    • Bring up the Monitor corresponding to the Target Node.
    • Then, while holding T, double-click into the bar chart area of the desired state.

For a Normal Node:

  • Option 1:
    • Right-click on the desired node and select Set as Target Node from the Node Context Menu.
    • Then, check the Target Node box and select the desired Target State from the drop-down list.
  • Option 2:
    • Bring up the Monitor of the desired node in the Monitor Panel.
    • Then, while holding T, double-click into the bar chart area of the desired state.
    • This sets the Target Node and the Target State at the same time.

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