EPIA'03 - 11th Portuguese Conference on Artificial Intelligence

	Session: December 6, 10:0-11:30, Room A
Title:	Adaptation to Drifting Concepts
	Gladys Castillo, João Gama, Pedro Medas
Abstract:	Incremental supervised learning assumes the stability of the target concept over time. Nevertheless in many real-user modeling systems, where the data is collected over an extended period of time, the learning task can be complicated by changes in the distribution underlying the data. This problem is known in machine learning as concept drift. The main idea behind Statistical Quality Control is to monitor the stability of one or more quality characteristics in a production process which generally shows some variation over time. In this paper we present a method for handling concept drift based on Shewhart P-Charts in an on-line framework for supervised learning. We explore the use of two alternatives P-charts, which differ only by the way they estimate the target value to set the center line. Experiments with simulated concept drift scenarios in the context of a user modeling prediction task compare the propose method with other adaptive approaches. The results show that, both P-Charts consistently recognize concept changes, and that the learner can adapt quickly to these changes to maintain its performance level.

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