Quasi-Newton particle Metropolis-Hastings applied to intractable likelihood models

Particle Metropolis-Hastings enables Bayesian parameter inference in general nonlinear state space models (SSMs). However, in many implementations a random walk proposal is used and this can result in poor mixing if not tuned correctly using tedious pilot runs. Therefore, we consider a new proposal inspired by quasi-Newton algorithms that achieves better mixing with less tuning. Compared to other Hessian based proposals, it only requires estimates of the gradient of the log-posterior. A possible application of this new proposal is parameter inference in the challenging class of SSMs with intractable likelihoods. We exemplify this application and the benefits of the new proposal by modelling log-returns of future contracts on coffee by a stochastic volatility model with symmetric $\alpha$-stable observations.