1. A method of generating a model having a plurality of clusters for describing data each of which describes a plurality of data points of observed data in a data corpus, comprising: performing a probabilistic analysis on a portion of the observed data to obtain probabilistically analyzed data including using the probabilistically analyzed data to identify a search space as a subset of the observed data by identifying observed data not sufficiently well described by previously generated clusters; within the step of performing the probabilistic analysis, performing a spectral analysis on data in the search space to obtain spectrally analyzed data; and generating a new cluster that includes a subset of the data in the search space based on the probabilistically analyzed data and the spectrally analyzed data and adding the cluster to the model.