Questions tagged [bayesian-network]

For questions related to Bayesian networks, the generic example of a directed probabilistic graphical model. Includes dynamic Bayesian networks, e.g. Hidden Markov Models (HMMs) and Kalman Filters. For applications of Bayesian networks in any field, e.g. machine learning. NOT for general questions about Bayes' theorem, Bayesian statistics, conditional probabilities, networks, or graph theory.

Bayesian networks are probabilistic graphical models which represent a set of random variables and their conditional dependencies using directed acyclic graph (DAG)... Bayesian networks are DAGs whose nodes represent random variables and whose edges represent conditional dependencies.

A dynamic Bayesian network is a Bayesian network which relates variables to each other over adjacent time steps. They generalize both Hidden Markov Models and Kalman filters.

The term hierarchical model is sometimes considered a particular type of Bayesian network, but has no formal definition. In general any moderately complex Bayesian network is usually termed "hierarchical".

Although Bayesian networks are often used to represent causal relationships, this need not be the case.

Bayesian networks are used for modeling beliefs in computational biology and bioinformatics (gene regulatory networks, protein structure, gene expression analysis, learning epistasis from GWAS data sets) medicine, biomonitoring, document classification, information retrieval, semantic search, image processing, data fusion, decision support systems, engineering, sports betting, gaming, law, study design and risk analysis.

The term "Bayesian networks" was coined by Judea Pearl in 1985.

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Partly undirected Bayesian Network

I am designing a Dynamic Bayesian Network, but I am a little confused about some definition of DBN and Markov network. In my network, the edges from the hidden nodes of last frame to the current frame are directed as normal. And the edges from the…
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How to calculate P(X|W,Z) in a Bayesian network?

Bayesian net I can see that $P(X,Y,W,Z)$ = $P(X|Y,Z)P(Y|W,Z)P(W)P(Z)$. I did the following till now to calculate $P(X|W,Z)$: $P(X|W,Z)$ = $P(X|Y,W,Z)$ + $P(X|\overline{Y},W,Z)$ = $P(X,Y,W,Z)P(Y,W,Z)$ + $P(X,\overline{Y},W,Z)P(\overline{Y},W,Z)$ =…
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Practical computation time needed to perform approximate inferences with a trained Bayesian network.

I have a task of estimating probabilities of events occurring for which a Bayesian Network appears to be an excellent modelling choice. Ample data and computational time will be available for training. The estimates can be fairly rough…
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How is the lambda message computed? (Bayesian network)

Currently reading through Pearl [1988]. Here is the Bayesian network shown in the book: Bayesian network Where the probabilities of each $X$ node are given by the probability vector $(q_i,p_i)$ where $q_i$ is the probability of the $X$ input being…
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Independence in Belief Networks

The belief network for the following questions is given below: Q1: Which variables must be independent of A given C and S according to the belief network above? My ans: Since C is given, there is no active trail through A-C-D, hence D is…
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calculate probability using variable elimination

Consider the following Conditional probability for the Bayesian Network: By using variable elimination, how to calculate the following probability? I am summing all the terms related to $E$, then will do for $L$, and then $T$, but I am not sure…
Toey
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How do I find the P(B | D = T) in this bayesina netowrk?

How to find P(B | D = T) in the following Bayesian network?
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Directed edges in Bayes net could have no effect?

After taking a risk analysis course, I am getting myself familiar with Bayes nets. Currently, I am looking at a common example of whether to take an umbrella on a walk. This is in the context of Norsys's Netica application, where decision nodes…
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How do I calculate the diagnostic inference for Bayes Net with multiple evidence and hidden variable?

I have a Bayes Net for a tsunami alarm at nuclear power plants that looks like this: Top node is "Tsunami" = (T or F) is the ground truth of whether there is a Tsunami approaching. There is a "Wave Sensor Faulty" node, child of top node, which if…
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Bayesian Network Enumeration

I want to calculate P(L) for the given Bayesian Network. The solution that I am presented with by the lecturer is 0.170 My calculation path is as following. Since we know that in a Bayesian network the probability distribution of a random variable…
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conditional independence on Bayes graph

I am confusing on conditional independence on Bayes graph. a graph: P6 ↓ P1 → P3 → P4 → P5 ↓ P7 Please kindly let me know if below understanding is correct or not? (1) P1 and P6 given P5 is NOT conditional…
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find d-seperation in DAG

i got a question regarding DAGs and d-seperation within the theme Bayesian Networks. In Task d) i am supposed to check for the following d-seperations. But i am struggeling. My other excercises provide some intel, but not enough for me to get…
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Conditional Probability Calculation in Bayes Net

Say I have a simple Bayes Net that appears like that in the picture and am giving the following probabilities: $P(y|x) = 0.5$ $P(z|x)=0.4$ $P(y|\bar{x})=0.8$ $P(z|\bar{x}) = 0.9 $ How would I calculate the following, or is it not possible to…
nsg
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How do I make sure that the nodes in a Bayesian network that I'm building all satisfy the Markov condition without painful trial-and-error?

I think that I understand the fundamentals of a Bayesian network and am trying to put that into practice by making a sample one, its size being about 20 nodes. But I'm struggling to see how to assign probabilities to all the nodes in such a way that…
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Bayesian Network, Sprinkler,Rain,Grass-Wet Example

I found an example in wikipedia stating: Suppose that there are two events which could cause grass to be wet: either the sprinkler is on or it's raining. Also, suppose that the rain has a direct effect on the use of the sprinkler (namely that when…
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