Invariant Probabilistic Prediction
Alexander Henzi Xinwei Shen Michael Law Peter Bühlmann
In recent years, there has been a growing interest in statistical methods
that exhibit robust performance under distribution changes between training and
test data. While most of the related research focuses on point predictions with
the squared error loss, this article turns the focus towards probabilistic
predictions, which aim to comprehensively quantify the uncertainty of an
outcome variable given covariates. Within a causality-inspired framework, we
investigate the invariance and robustness of probabilistic predictions with
respect to proper scoring rules. We show that arbitrary distribution shifts do
not, in general, admit invariant and robust probabilistic predictions, in
contrast to the setting of point prediction. We illustrate how to choose
evaluation metrics and restrict the class of distribution shifts to allow for
identifiability and invariance in the prototypical Gaussian heteroscedastic
linear model. Motivated by these findings, we propose a method to yield
invariant probabilistic predictions, called IPP, and study the consistency of
the underlying parameters. Finally, we demonstrate the empirical performance of
our proposed procedure on simulated as well as on single-cell data.