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Sensitivity — Expert Assessments

Context

  • In the context of Bayesian networks designed by a group of experts via brainstorming, e.g., with BEKEE, the Assessment Sensitivity Analysis allows you to quantify the uncertainty associated with the probabilities generated through the expert consensus.
  • BayesiaLab estimates the variability of the probabilities by generating a set of networks based on the assessments given by the experts.
  • Below are three different generation methods, ranked in increasing order of randomness:
    1. An expert is randomly chosen for each network;
    2. An expert is randomly chosen for each node of the network;
    3. An expert is randomly chosen for each conditional distribution, i.e., each combination of the node's parents.

New Feature: Multi-Curve Graph

  • Version 7.0 now allows plotting the density graph of all the states of a node in the same graph.

Example

  • Let's use the network below, designed by a group of four experts:

  • The experts have given the following distributions for the node Manager Quality:

which results in this consensual distribution (that takes into account the confidence level of each expert):

  • For such root node (i.e. without parent), the distribution of the node is defined by a unique expert, for the three types of network generation methods.

  • Let's focus now on the node Internal Relations. It has two binary parents, defining thus 4 conditional probability distributions that have been assessed by our four experts, resulting in the following consensual conditional distributions:

  • For this kind of node with parents, the third network generation method can lead to define the table by using four different experts.

  • Below is the marginal distribution inferred with the consensual Bayesian network:

  • Let's generate 1,000 networks for measuring the variability associated with the marginal distribution of this node. We randomly choose an expert per conditional distribution:

  • As the multi-curve graph below indicates, the probability of Internal Relations=Weak ranges from 19% to 65%, with a mean value of 39%.


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