Nonparametric FBST for Validating Linear Models

TL;DR

This paper extends the Full Bayesian Significance Test (FBST) to nonparametric settings using Gaussian processes, enabling validation of linear models and automatic variable selection in complex data scenarios.

Contribution

It introduces a nonparametric FBST framework with Gaussian process priors for testing linear model hypotheses, expanding FBST applicability beyond parametric models.

Findings

Enables hypothesis testing for linear models in nonparametric contexts.

Provides a procedure for automatic variable selection.

Allows assessment of model adequacy considering measurement errors.

Abstract

The Full Bayesian Significance Test (FBST) possesses many desirable aspects, such as dismissing the need for hypotheses to have positive prior probability and providing a measure of evidence against $H_0$. Still, few attempts have been made to bring the FBST to nonparametric settings, with the main drawback being the need to obtain the highest posterior density (HPD) in a function space. In this work, we use a Gaussian processes prior to derive the FBST for hypotheses of the type $$ H_0: g(\boldsymbol{x}) = \boldsymbol{b}(\boldsymbol{x})\boldsymbol{\beta}, \quad \forall \boldsymbol{x} \in \mathcal{X}, \quad \boldsymbol{\beta} \in \mathbb{R}^k, $$ where $g(\cdot)$ is the regression function, $\boldsymbol{b}(\cdot)$ is a vector of linearly independent linear functions -- such as $\boldsymbol{b}(\boldsymbol{x}) = \boldsymbol{x}'$ -- and $\mathcal{X}$ is the covariates' domain. We also make use of pragmatic hypotheses to verify if the data might be compatible with a linear model when factors such as measurement errors or utility judgments are accounted for. This contribution extends the theory of the FBST, allowing its application in nonparametric settings and providing a procedure that easily tests if linear models are adequate for the data and that can automatically perform variable selection.