A Fast and Calibrated Computer Model Emulator: An Empirical Bayes Approach

TL;DR

This paper introduces an empirical Bayes method using Gaussian process emulators for fast, calibrated predictions of physical quantities from computationally expensive models, with proven consistency and demonstrated efficiency.

Contribution

It develops a novel empirical Bayes framework with Gaussian process calibration for computer models, providing theoretical guarantees and practical efficiency.

Findings

The approach achieves accurate predictions with closed-form solutions.

Posterior consistency is rigorously established.

Method demonstrates computational efficiency in simulations and real data.

Abstract

Mathematical models implemented on a computer have become the driving force behind the acceleration of the cycle of scientific processes. This is because computer models are typically much faster and economical to run than physical experiments. In this work, we develop an empirical Bayes approach to predictions of physical quantities using a computer model, where we assume that the computer model under consideration needs to be calibrated and is computationally expensive. We propose a Gaussian process emulator and a Gaussian process model for the systematic discrepancy between the computer model and the underlying physical process. This allows for closed-form and easy-to-compute predictions given by a conditional distribution induced by the Gaussian processes. We provide a rigorous theoretical justification of the proposed approach by establishing posterior consistency of the estimated physical process. The computational efficiency of the methods is demonstrated in an extensive simulation study and a real data example. The newly established approach makes enhanced use of computer models both from practical and theoretical standpoints.