Understanding how to read Bayesian networks












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Below is an example that I want to talk about:
enter image description here



I'm going to define variable names based on the first letter as described in the bubbles. One question I have is how would I calculate $P(M|B)$? This is what I got so far: $$P(M|B) = dfrac{P(M,B)}{P(B)}$$
Since $P(B)$ is known then I move on to the numerator:
$$P(M,B) = P(M,B,J,E,A)+P(M,B,neg J, E,A)+P(M,B,J,neg E,A)+P(M,B,J, E,neg A)+P(M,B,neg J,neg E,A)+P(M,B,neg J, E,neg A)+P(M,B,J, neg E,neg A)+P(M,B,neg J, neg E,neg A)$$
Is this really the way? I'm surprised to see how much computation I have to do for such a small problem. Am I doing this correctly?










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    1












    $begingroup$


    Below is an example that I want to talk about:
    enter image description here



    I'm going to define variable names based on the first letter as described in the bubbles. One question I have is how would I calculate $P(M|B)$? This is what I got so far: $$P(M|B) = dfrac{P(M,B)}{P(B)}$$
    Since $P(B)$ is known then I move on to the numerator:
    $$P(M,B) = P(M,B,J,E,A)+P(M,B,neg J, E,A)+P(M,B,J,neg E,A)+P(M,B,J, E,neg A)+P(M,B,neg J,neg E,A)+P(M,B,neg J, E,neg A)+P(M,B,J, neg E,neg A)+P(M,B,neg J, neg E,neg A)$$
    Is this really the way? I'm surprised to see how much computation I have to do for such a small problem. Am I doing this correctly?










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      Below is an example that I want to talk about:
      enter image description here



      I'm going to define variable names based on the first letter as described in the bubbles. One question I have is how would I calculate $P(M|B)$? This is what I got so far: $$P(M|B) = dfrac{P(M,B)}{P(B)}$$
      Since $P(B)$ is known then I move on to the numerator:
      $$P(M,B) = P(M,B,J,E,A)+P(M,B,neg J, E,A)+P(M,B,J,neg E,A)+P(M,B,J, E,neg A)+P(M,B,neg J,neg E,A)+P(M,B,neg J, E,neg A)+P(M,B,J, neg E,neg A)+P(M,B,neg J, neg E,neg A)$$
      Is this really the way? I'm surprised to see how much computation I have to do for such a small problem. Am I doing this correctly?










      share|cite|improve this question









      $endgroup$




      Below is an example that I want to talk about:
      enter image description here



      I'm going to define variable names based on the first letter as described in the bubbles. One question I have is how would I calculate $P(M|B)$? This is what I got so far: $$P(M|B) = dfrac{P(M,B)}{P(B)}$$
      Since $P(B)$ is known then I move on to the numerator:
      $$P(M,B) = P(M,B,J,E,A)+P(M,B,neg J, E,A)+P(M,B,J,neg E,A)+P(M,B,J, E,neg A)+P(M,B,neg J,neg E,A)+P(M,B,neg J, E,neg A)+P(M,B,J, neg E,neg A)+P(M,B,neg J, neg E,neg A)$$
      Is this really the way? I'm surprised to see how much computation I have to do for such a small problem. Am I doing this correctly?







      bayesian bayesian-network






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      asked Jan 24 at 5:37









      Ayumu KasuganoAyumu Kasugano

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          $begingroup$

          Well, the joint probability distribution is
          $$p(B,E,A,J,M) = p(B) p(E) p(Amid B,E) p(Jmid A) p(Mmid A).$$
          What your are looking for is the marginal distribution
          $$p(M,B) = sum_{E,A,J} p(B,E,A,J,M),$$
          where the sum is over all values of $E,A,J$ and this is what you did right!






          share|cite|improve this answer









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            1 Answer
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            1 Answer
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            $begingroup$

            Well, the joint probability distribution is
            $$p(B,E,A,J,M) = p(B) p(E) p(Amid B,E) p(Jmid A) p(Mmid A).$$
            What your are looking for is the marginal distribution
            $$p(M,B) = sum_{E,A,J} p(B,E,A,J,M),$$
            where the sum is over all values of $E,A,J$ and this is what you did right!






            share|cite|improve this answer









            $endgroup$


















              0












              $begingroup$

              Well, the joint probability distribution is
              $$p(B,E,A,J,M) = p(B) p(E) p(Amid B,E) p(Jmid A) p(Mmid A).$$
              What your are looking for is the marginal distribution
              $$p(M,B) = sum_{E,A,J} p(B,E,A,J,M),$$
              where the sum is over all values of $E,A,J$ and this is what you did right!






              share|cite|improve this answer









              $endgroup$
















                0












                0








                0





                $begingroup$

                Well, the joint probability distribution is
                $$p(B,E,A,J,M) = p(B) p(E) p(Amid B,E) p(Jmid A) p(Mmid A).$$
                What your are looking for is the marginal distribution
                $$p(M,B) = sum_{E,A,J} p(B,E,A,J,M),$$
                where the sum is over all values of $E,A,J$ and this is what you did right!






                share|cite|improve this answer









                $endgroup$



                Well, the joint probability distribution is
                $$p(B,E,A,J,M) = p(B) p(E) p(Amid B,E) p(Jmid A) p(Mmid A).$$
                What your are looking for is the marginal distribution
                $$p(M,B) = sum_{E,A,J} p(B,E,A,J,M),$$
                where the sum is over all values of $E,A,J$ and this is what you did right!







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 24 at 8:39









                WuestenfuxWuestenfux

                5,1271513




                5,1271513






























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