Inference for log Gaussian Cox processes using an approximate marginal posterior

Abstract: The log Gaussian Cox process is a flexible class of point pattern models for capturing spatial and spatio-temporal dependence for point patterns. Model fitting requires approximation of stochastic integrals which is implemented through discretization of the domain of interest. With fine scale discretization, inference based on Markov chain Monte Carlo is computationally heavy because of the cost of repeated iteration or inversion or Cholesky decomposition (cubic order) of high dimensional covariance matrices associated with latent Gaussian variables. Furthermore, hyperparameters for latent Gaussian variables have strong dependence with sampled latent Gaussian variables. Altogether, standard Markov chain Monte Carlo strategies are inefficient and not well behaved. In this paper, we propose an efficient computational strategy for fitting and inferring with spatial log Gaussian Cox processes. The proposed algorithm is based on a pseudo-marginal Markov chain Monte Carlo approach. We estimate an approximate marginal posterior for parameters of log Gaussian Cox processes and propose comprehensive model inference strategy. We provide details for all of the above along with some simulation investigation for the univariate and multivariate settings. As an example, we present an analysis of a point pattern of locations of three tree species, exhibiting positive and negative interaction between different species.