Possibilistic inferential models: a review
Ryan Martin
TL;DR
This paper surveys possibilistic inferential models (IMs), which map observed data $Z$ to a possibility-based uncertainty quantification instead of precise probabilities, thereby achieving fully Bayesian-like conditional inference with frequentist calibration and avoiding the unreliability of probabilistic methods under vacuous priors. It develops a likelihood-based construction that yields a contour $\pi_z(\theta)$, and from it upper and lower possibility measures $\Pi_z$ and $\amalg_z$, guaranteeing strong validity and asymptotic efficiency via a possibilistic Bernstein–von Mises theorem. Computation is advanced through sampling from credal sets and inner probabilistic approximations, enabling practical uncertainty quantification even in nuisance-parameter settings and for marginal/inference-on-risk problems. The framework also connects to conformal prediction for predictive inference and demonstrates compatibility with frequentist and Bayesian perspectives, while offering a principled alternative in contexts with limited prior information and complex uncertainty structures. Overall, possibilistic IMs provide a rigorous, flexible, and reliable approach to data-driven uncertainty quantification with broad applicability to risk minimization and prediction tasks in statistics and data science.
Abstract
An inferential model (IM) is a model describing the construction of provably reliable, data-driven uncertainty quantification and inference about relevant unknowns. IMs and Fisher's fiducial argument have similar objectives, but a fundamental distinction between the two is that the former doesn't require that uncertainty quantification be probabilistic, offering greater flexibility and allowing for a proof of its reliability. Important recent developments have been made thanks in part to newfound connections with the imprecise probability literature, in particular, possibility theory. The brand of possibilistic IMs studied here are straightforward to construct, have very strong frequentist-like reliability properties, and offer fully conditional, Bayesian-like (imprecise) probabilistic reasoning. This paper reviews these key recent developments, describing the new theory, methods, and computational tools. A generalization of the basic possibilistic IM is also presented, making new and unexpected connections with ideas in modern statistics and machine learning, e.g., bootstrap and conformal prediction.
