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|    Message 674 of 1,954    |
|    robert_dodier@yahoo.com to All    |
|    Re: Why use graphic approach for Bayesia    |
|    29 Mar 05 20:55:02    |
      XPost: comp.ai.neural-nets, comp.theory, sci.stat.math              > Bayesian networks use the same inference tool       > of Bayesian methods, so why use a network to       > model? Any NEW properties or advantage       > could be generated?              A Bayesian network is just a visualization of a       joint probability distribution -- it is a means of       focusing on dependencies among variables       and ignoring all other details.              My experience has been that dependencies       have more effect on results than choosing       one distribution or another. Reasonable choices       of distributions tend to yield similar results,       while making two variables dependent or       independent may have a very broad (and       interesting) qualitative effect.              Unfortunately, changing the dependencies       may easily change a tractable problem into       an intractable problem; the relevant characteristic       is the presence or absence of loops (undirected       cycles) in the network. I'll mention that models       for temporal problems usually have loops.              Exact methods for loopy networks are known       for a rather limited set of distributions; this is       the major limitation of existing Bayesian network       software.              My advice to the original poster is to formulate       one or more Bayesian networks of interest,       and then look for software which can handle       them; don't let the capabilities of a software       package steer your project.              For what it's worth,       Robert Dodier              [ comp.ai is moderated. To submit, just post and be patient, or if ]       [ that fails mail your article to |
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