Erratum to: J Intell Inf Syst

DOI 10.1007/s10844-016-0405-8

Figure 5 in the original version of this article was incorrect. The correct figure is shown next page and in the current version.

Fig. 5
figure 1

Visualization of the hierarchies of the tmc2007 and enron datasets and the number of examples in the nodes of the hierarchies represented by the size of the circles. Circles of the original labels are annotated, while the circles that represent the meta-labels are not annotated