Abstract

Abstract

Abstract

Abstract
Several predictive systems are nowadays vital for operations and decision support. The quality of these systems is most of the time defined by their average accuracy which has low or no information at all about the estimated error of each individual prediction. In these cases, users should be allowed to associate a measure of reliability to each prediction. However, with the advent of data streams, batch state-of-the-art reliability estimates need to be redefined. In this chapter we adapt and evaluate five empirical measures for online reliability estimation of individual predictions: similarity-based (k-NN) error, local sensitivity (bias and variance) and online bagging predictions (bias and variance). Evaluation is performed with a neural network base model on two different problems, with results showing that online bagging and k-NN estimates are consistently correlated with the error of the base model. Furthermore, we propose an approach for correcting individual predictions based on the CNK reliability estimate. Evaluation is done on a real-world problem (prediction of the electricity load for a selected European geographical region), using two different regression models: neural network and the k nearest neighbors algorithm. Comparison is performed with corrections based on the Kalman filter. The results show that our method performs better than the Kalman filter, significantly improving the original predictions to more accurate values.

Abstract

Abstract
Sensor networks consist of distributed autonomous devices that cooperatively monitor an environment. Sensors are equipped with capacities to store information in memory, process this information and communicate with their neighbors. Processing data streams generated from wireless sensor networks has raised new research challenges over the last few years due to the huge numbers of data streams to be managed continuously and at a very high rate. The book provides the reader with a comprehensive overview of stream data processing, including famous prototype implementations like the Nile system and the TinyOS operating system. The set of chapters covers the state-of-art in data stream mining approaches using clustering, predictive learning, and tensor analysis techniques, and applying them to applications in security, the natural sciences, and education. This research monograph delivers to researchers and graduate students the state of the art in data stream processing in sensor networks. The huge bibliography offers an excellent starting point for further reading and future research. © Springer-Verlag Berlin Heidelberg 2007. All rights are reserved.