Conditional Densities and Efficient Models in Infinite Exponential Families

The exponential family is one of the most powerful and widely used classes of models in statistics. A method was recently developed to fit this model when the natural parameter and sufficient statistic are infinite dimensional, using a score matching approach. The infinite exponential family is a natural generalisation of the finite case, much like the Gaussian and Dirichlet processes generalise their respective finite modfels. In this talk, I'll describe two recent results which make this model more applicable in practice, by reducing the computational burden and improving performance for high-dimensional data. The firsrt is a Nytsrom-like approximation to the full solution. We prove that this approximate solution has the same consistency and convergence rates as the full-rank solution (exactly in Fisher distance, and nearly in other distances), with guarantees on the degree of cost and storage reduction. The second result is a generalisation of the model family to the conditional case, again with consistency guarantees. In experiments, the conditional model generally outperforms a competing approach with consistency guarantees, and is competitive with a deep conditional density model on datasets that exhibit abrupt transitions and heteroscedasticity.