Recent advances in probabilistic deep learning enable efficient amortized Bayesian inference in settings where the likelihood function is only implicitly defined by a simulation program (simulation-based inference; SBI). But how faithful is such inference if the simulation represents reality somewhat inaccurately, that is, if the true system behavior at test time deviates from the one seen during training? We conceptualize the types of such model misspecification arising in SBI and systematically investigate how the performance of neural posterior approximators gradually deteriorates as a consequence, making inference results less and less trustworthy. To notify users about this problem, we propose a new misspecification measure that can be trained in an unsupervised fashion (i.e., without training data from the true distribution) and reliably detects model misspecification at test time. Our experiments clearly demonstrate the utility of our new measure both on toy examples with an analytical ground-truth and on representative scientific tasks in cell biology, cognitive decision making, disease outbreak dynamics, and computer vision. We show how the proposed misspecification test warns users about suspicious outputs, raises an alarm when predictions are not trustworthy, and guides model designers in their search for better simulators.

在模拟基础推理中，我们研究了模拟程序不准确表示真实系统行为对推理结果的影响，并提出了一种能够可靠检测模型错误规范性的新度量标准。实验证明，这个度量标准对于警示用户可疑输出、当预测结果不可靠时发出警告，并引导模型设计者寻找更好的模拟器具有很大的实用性。

使用神经网络检测摊余贝叶斯推断中的模型错误：一项扩展研究