Robust Amortized Simulation-Based Inference via Learned Error Models

Recent advances in neural density estimation have enabled amortized Bayesian inference for complex stochastic simulators. However, these methods rely on simulators accurately reflecting the true data-generating process and can degrade significantly under model misspecification. We consider the setting where multiple unlabeled observations are available and introduce robust variational neural posterior estimation (RVNP), an amortized Bayesian inference method that uses an importance-weighted autoencoder to jointly learn a misspecification-robust posterior and an explicit error model that captures the misspecification gap. Our results show that RVNP can recover robust posterior inference in a data-driven and interpretable manner, outperforming previous methods across multiple metrics and misspecified benchmarks.