Combine and Conquer: A Meta-Analysis on Data Shift and Out-of-Distribution Detection

TL;DR

This paper presents a universal, statistically grounded method for combining multiple out-of-distribution detection scores, significantly improving robustness and performance in diverse scenarios by framing the problem as a multi-variate hypothesis test.

Contribution

It introduces a novel meta-analysis framework that normalizes and combines OOD detection scores, enabling more effective and interpretable out-of-distribution detection.

Findings

Enhanced robustness across various OOD scenarios

Effective combination of diverse detection scores

First framework to unify decision boundaries in this context

Abstract

This paper introduces a universal approach to seamlessly combine out-of-distribution (OOD) detection scores. These scores encompass a wide range of techniques that leverage the self-confidence of deep learning models and the anomalous behavior of features in the latent space. Not surprisingly, combining such a varied population using simple statistics proves inadequate. To overcome this challenge, we propose a quantile normalization to map these scores into p-values, effectively framing the problem into a multi-variate hypothesis test. Then, we combine these tests using established meta-analysis tools, resulting in a more effective detector with consolidated decision boundaries. Furthermore, we create a probabilistic interpretable criterion by mapping the final statistics into a distribution with known parameters. Through empirical investigation, we explore different types of shifts, each exerting varying degrees of impact on data. Our results demonstrate that our approach significantly improves overall robustness and performance across diverse OOD detection scenarios. Notably, our framework is easily extensible for future developments in detection scores and stands as the first to combine decision boundaries in this context. The code and artifacts associated with this work are publicly available\footnote{\url{https://github.com/edadaltocg/detectors}}.