Fig. 1.

The effect of creating two specialized classifiers. It is clear that the performance of classifiers for ‘seen before’ and ‘new’ sites should be evaluated separately. Furthermore, the figure shows that it is worth training specialized classifiers: (A) Identification of ‘seen before’ sites. The classifier trained to identify ‘seen before’ sites is somewhat better at identifying such sites than the classifier trained to identify ‘new’ sites. (B) Identification of ‘new’ sites. The classifier trained to identify ‘new’ sites performs better than the classifier trained to identify ‘seen before’ sites at identifying ‘new’ sites.