TY - CHAP U1 - Konferenzveröffentlichung A1 - Wiegand, Michael A1 - Leidner, Jochen L. A1 - Klakow, Dietrich ED - Calzolari, Nicoletta ED - Choukri, Khalid ED - Maegaard, Bente ED - Mariani, Joseph ED - Odijk, Jan ED - Piperidis, Stelios ED - Tapias, Daniel T1 - Cost-Sensitive Learning in Answer Extraction T2 - Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08), May 28-30, 2008, Marrakech, Morocco N2 - One problem of data-driven answer extraction in open-domain factoid question answering is that the class distribution of labeled training data is fairly imbalanced. In an ordinary training set, there are far more incorrect answers than correct answers. The class-imbalance is, thus, inherent to the classification task. It has a deteriorating effect on the performance of classifiers trained by standard machine learning algorithms. They usually have a heavy bias towards the majority class, i.e. the class which occurs most often in the training set. In this paper, we propose a method to tackle class imbalance by applying some form of cost-sensitive learning which is preferable to sampling. We present a simple but effective way of estimating the misclassification costs on the basis of class distribution. This approach offers three benefits. Firstly, it maintains the distribution of the classes of the labeled training data. Secondly, this form of meta-learning can be applied to a wide range of common learning algorithms. Thirdly, this approach can be easily implemented with the help of state-of-the-art machine learning software. KW - Computerlinguistik KW - Information Extraction KW - Maschinelles Lernen KW - Natürliche Sprache KW - Statistical methods KW - Machine Learning KW - Acquisition KW - Question Answering Y1 - 2008 U6 - https://nbn-resolving.org/urn:nbn:de:bsz:mh39-85373 UN - https://nbn-resolving.org/urn:nbn:de:bsz:mh39-85373 UR - https://aclanthology.info/papers/L08-1293/l08-1293 SN - 2-9517408-4-0 SB - 2-9517408-4-0 SP - 711 EP - 714 PB - European Language Resources Association CY - Paris ER -