Attention-Based Feature Online Conformal Prediction for Time Series

TL;DR

This paper introduces AFOCP, an attention-based feature conformal prediction method for time series that improves prediction set efficiency and adapts to non-stationarity, outperforming standard OCP.

Contribution

AFOCP innovatively combines feature-space calibration with attention mechanisms to enhance conformal prediction for time series.

Findings

Reduces prediction interval size by up to 88% compared to OCP.

Maintains coverage guarantees under distribution shifts.

Demonstrates effectiveness on synthetic and real-world datasets.

Abstract

Online conformal prediction (OCP) wraps around any pre-trained predictor to produce prediction sets with coverage guarantees that hold irrespective of temporal dependencies or distribution shifts. However, standard OCP faces two key limitations: it operates in the output space using simple nonconformity (NC) scores, and it treats all historical observations uniformly when estimating quantiles. This paper introduces attention-based feature OCP (AFOCP), which addresses both limitations through two key innovations. First, AFOCP operates in the feature space of pre-trained neural networks, leveraging learned representations to construct more compact prediction sets by concentrating on task-relevant information while suppressing nuisance variation. Second, AFOCP incorporates an attention mechanism that adaptively weights historical observations based on their relevance to the current test point, effectively handling non-stationarity and distribution shifts. We provide theoretical guarantees showing that AFOCP maintains long-term coverage while provably achieving smaller prediction intervals than standard OCP under mild regularity conditions. Extensive experiments on synthetic and real-world time series datasets demonstrate that AFOCP consistently reduces the size of prediction intervals by as much as $88\%$ as compared to OCP, while maintaining target coverage levels, validating the benefits of both feature-space calibration and attention-based adaptive weighting.