Bayesian Network Homework: Equations & Solutions

In summary, the conversation discusses solving for conditional probabilities in various scenarios. In part A, the formula used is P(B|JC) = P(B,JC)/P(JC), while in part B it is P(B|!JC, MC) = P(B, !JC, MC) / P(!JC, MC). For part C, the focus is on computing P(JC, MC), which can be found by examining all possible cases. The probability of John calling and Mary calling can be found by dividing the total number of cases where both occur by the total number of cases. The probabilities of John calling and Mary calling individually can also be found by examining the different cases.
  • #1
puppydog
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Homework Statement



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Homework Equations

The Attempt at a Solution



For part A I solved for P(B|JC) = P(B,JC)/P(JC)
For part B I am thinking P(B|!JC, MC) = P(B, !JC, MC) / P(!JC, MC)
For part C I am thinking P(JC|MC) = P(JC, MC)/P(MC)

Am I on track with these equations? Especially for part c? How do I compute P(JC, MC)?
 
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  • #2
The probability that john calls and mary calls can be found by examining all cases:
Burgled --> Alarm --> John calls =A1
Burgled --> Alarm --> Mary calls=A2
Not burgled --> Alarm --> John calls =B1
Not burgled --> Alarm --> Mary calls =B2
Burgled --> No Alarm --> John might call, but Mary won't =C1
Not Burgled --> No Alarm --> John might call, but Mary won't =D1
edit: P(JC & MC) = A1*A2/p(Burgled + Alarm) + B1*B2/p(Not burgled + alarm) + C1*0/p(burgled and no alarm) + D1*0/p(not burgled and no alarm)
P(MC) = A2+B2+0+0
P(JC) = A1+B1+C1+D1
 

Related to Bayesian Network Homework: Equations & Solutions

1. What are Bayesian networks and why are they used in homework assignments?

Bayesian networks are graphical models used to represent and analyze probabilistic relationships between variables. They are often used in homework assignments to help students understand and apply concepts related to conditional probability and statistical inference.

2. How do you construct a Bayesian network for a given problem?

To construct a Bayesian network, you first identify the variables involved in the problem and their relationships. Then, you draw a directed acyclic graph (DAG) where each node represents a variable and the edges represent the dependencies between variables. Finally, you assign conditional probability tables (CPTs) to each node based on the given information.

3. What is the difference between a Bayesian network and a regular probability tree?

While both Bayesian networks and probability trees can be used to represent probabilistic relationships, Bayesian networks are more efficient in handling problems with a large number of variables. This is because Bayesian networks allow for the representation of complex dependencies between variables, while probability trees can become unwieldy and difficult to interpret in such cases.

4. How do you use a Bayesian network to solve a homework problem?

To solve a homework problem using a Bayesian network, you first use the given information to construct the network and assign probabilities to the nodes. Then, you use the network to calculate the probabilities of different events or variables, either through direct calculation or using Bayes' theorem. Finally, you use the calculated probabilities to answer the specific question or solve the problem.

5. Are there any common mistakes students make when using Bayesian networks for homework?

One common mistake students make when using Bayesian networks is not properly identifying and representing the relationships between variables. This can lead to incorrect calculations and solutions. Another mistake is not understanding and properly using conditional probability and Bayes' theorem, which are essential concepts in Bayesian network analysis.

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