23.3.1 Method Summary Matrix
The following matrix (Table 23.1) provides a summary of the methods overviewed
in this chapter. Explicit performance numbers are not supplied because to our knowledge no such comprehensive comparison in fact exists. AL methods could be compared on an individual basis, but any results would be inconclusive. This is because
authors have a tendency to fix the predictive method and then apply one or more
compatible AL methods to compare performance. Moreover, AL methods are often
designed for a specific predictive method, and may therefore not have good performance when applied to a different method (which creates potentially misleading
results), or may not even be applicable if the underlying system is not able to provide the required information, e.g. distribution of rating estimates. For these reasons
we have opted to omit performances figures of any kind.