How to calculate node states in case of virtual evidence?

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nirzhor26
Posts: 6
Joined: Thu Jan 19, 2017 7:20 pm

How to calculate node states in case of virtual evidence?

Post by nirzhor26 » Wed Jan 25, 2017 8:04 pm

Can anyone suggest or show me any calculation how nodes are updated in case of virtual evidence given to any child node? Suppose, B is the child node of A. P(A)=0.9., P(B/A)= 0.6 and P(B/A')=0.8. In normal updating, P(B)= 0.62. If I put P(B)=0.9 as virtual evidence, after updating P(A) becomes 0.88 and P(B) becomes 0.94. I want to know how GeNIe is doing this calculation. Any suggestion please?

nirzhor26
Posts: 6
Joined: Thu Jan 19, 2017 7:20 pm

Re: How to calculate node states in case of virtual evidence?

Post by nirzhor26 » Wed Jan 25, 2017 8:19 pm

I am attaching the sample network here.
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sample network.xdsl
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nirzhor26
Posts: 6
Joined: Thu Jan 19, 2017 7:20 pm

Re: How to calculate node states in case of virtual evidence?

Post by nirzhor26 » Thu Jan 26, 2017 2:23 am

I have solved it. Thanks all.

viliop
Posts: 8
Joined: Mon Apr 23, 2018 6:28 am

Re: How to calculate node states in case of virtual evidence?

Post by viliop » Wed May 09, 2018 9:23 pm

Could you help about the way Genie calculate it?

marek [BayesFusion]
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Posts: 271
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Re: How to calculate node states in case of virtual evidence?

Post by marek [BayesFusion] » Tue May 15, 2018 2:59 pm

Virtual evidence implemented in GeNIe/SMILE is a standard calculation that you can read about in the literature. Here is one place where you can find information: https://www2.ee.washington.edu/techsite ... 4-0016.pdf. Essentially, virtual evidence corresponds to a child node of the evidence node that sends information up to the node in question. Parameters (conditional probability distribution) of the child node conditional on the evidence node correspond to the virtual evidence entered. I hope this helps,

Marek

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