1. A method for determining the class of an activity selected from a plurality of activities of interest, of a person based on sensor data, comprising the steps of: providing a plurality of kernel-based models, each corresponding to one of said activities of interest, obtaining a set of readings of said sensor data; generating estimates of said set of sensor data readings from at least some of said kernel-based models based on an input of said set of sensor data readings; comparing each said estimate of said set of sensor data readings to said input set of sensor data readings to determine a most similar estimate, and determining the class of activity corresponding to said input set of sensor data readings to be the class of the model that generated the most similar estimate.