Linking or matching databases is becoming increasingly important in many data mining projects, as linked data can contain information that is not available otherwise, or that would be too expensive to collect manually. A main challenge when linking large databases is the classification of the compared record pairs into matches and non-matches. In traditional record linkage, classification thresholds have to be set either manually or using an EM-based approach. More recently developed classification methods are mainly based on supervised machine learning techniques and thus require training data, which is often not available in real world situations or has to be prepared manually.