1. A network for estimating the error in the prediction output space of a predictive system model operating over a prediction input space, comprising: an input for receiving an input vector comprising a plurality of input values that occupy the prediction input space; an output for outputting an output prediction error vector that occupies an output space corresponding to the prediction output space of the predictive system model; and a processing layer for mapping the prediction input space to the prediction output space through a representation of the prediction error in the predictive system model to provide said output prediction error vector.