Solving real problems with Bayesian networks

by Norman Fenton, Queen Mary University of London

Bayesian networks give a foundation for tools that support decision making based on evidence collected and the probabilities of one thing causing another (see "What are the chances of that?").

The first algorithms that enabled Bayesian network models to be calculated on a computer were discovered separately by two different research groups in the late 1980s. Since then, a series of easy-to-use software packages have been developed that implement these algorithms, so that people without any knowledge of computing or statistics can easily build and run their own models.

These algorithms do ‘exact’ computations and can handle Bayesian networks for many different types of problems, but they can run into a barrier: when run on Bayesian networks beyond a certain size or complexity, they take too long to compute even on the world’s fastest computers. However, newer algorithms – which provide good approximate calculations rather than exact ones – have made it possible to deal with much larger problems, and this is a really exciting ongoing research area.