In the paper we discuss inducing rule-based classifiers from
imbalanced data, where one class (a minority class) is under-represented
in comparison to the remaining classes (majority classes). To improve
the ability of a classifier to recognize this class, we propose a new selective
pre-processing approach that is applied to data before inducing a
rule-based classifier. The approach combines selective filtering of the majority
classes with focused over-sampling of the minority class. Results
of a comparative experimental study show that our approach improves
sensitivity for the minority class while preserving the ability of a classifier
to recognize examples from the majority classes.