Why we should use BBNs
BBNs on their own enable us to model uncertain events and arguments about
them. The intuitive visual representation can be very useful in clarifying
previously opaque assumptions or reasonings hidden in the head of an expert. With BBNs,
it is possible to articulate expert beliefs about the dependencies between
different variables and BBNs allow an injection of scientific rigour when the
probability distributions associated with individual nodes are simply ‘expert opinions'. BBNs can expose some of the common fallacies in reasoning
due to misunderstanding of probability.
However, the real power of BBNs comes when we apply the rules of Bayesian
probability to propagate consistently the impact of evidence on the probabilities
of uncertain outcomes. A BBN will derive all the implications of the beliefs
that are input to it; some of these will be facts that can be checked against
observations, or simply against the experience of the decision makers themselves.