Parametric stochastic simulators are ubiquitous in science, often featuring high-dimensional input parameters and/or an intractable likelihood. Performing Bayesian parameter inference in this context can be challenging. We present a neural simulation-based inference algorithm which simultaneously offers simulation efficiency and fast empirical posterior testability, which is unique among modern algorithms. Our approach is simulation efficient by simultaneously estimating low-dimensional marginal posteriors instead of the joint posterior and by proposing simulations targeted to an observation of interest via a prior suitably truncated by an indicator function. Furthermore, by estimating a locally amortized posterior our algorithm enables efficient empirical tests of the robustness of the inference results. Since scientists cannot access the ground truth, these tests are necessary for trusting inference in real-world applications. We perform experiments on a marginalized version of the simulation-based inference benchmark and two complex and narrow posteriors, highlighting the simulator efficiency of our algorithm as well as the quality of the estimated marginal posteriors.
- Pub Date:
- July 2021
- Statistics - Machine Learning;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- Computer Science - Machine Learning;
- High Energy Physics - Phenomenology
- 10 pages. 27 pages with references and supplemental material. Implementation of experiments at https://github.com/bkmi/tmnre/. Ready-to-use implementation of underlying algorithm at https://github.com/undark-lab/swyft/. Accepted at NeurIPS 2021