RAxSS: Retrieval-Augmented Sparse Sampling for Explainable Variable-Length Medical Time Series Classification

Aydin Javadov, Samir Garibov, Tobias Hoesli, Qiyang Sun, Joseph Ollier, Florian von Wangenheim, Björn Schuller

Keywords: Time Series, Explainable AI, Healthcare, Epilepsy, Neuroscience

TL;DR: Retrieval-informed classifier for variable-length clinical time series: weight window predictions by within-recording similarity and aggregate in probability space. Competitive on multicenter iEEG with clear, clinician-friendly evidence trails.

Abstract:

Medical time series analysis is challenging due to data sparsity, noise, and highly variable recording lengths. Prior work has shown that stochastic sparse sampling effectively handles variable-length signals, while retrieval-augmented approaches improve
explainability and robustness to noise and weak temporal correlations. In this study, we generalize the stochastic sparse sampling framework for retrieval-informed classification. Specifically, we weight window predictions by within-channel similarity and aggregate them in probability space, yielding convex series-level scores and an explicit evidence trail for explainability. Our method achieves competitive iEEG classification performance and provides practitioners with greater transparency and explainability. We evaluate our method in iEEG recordings collected in four medical centers, demonstrating its potential for reliable and explainable clinical variable-length time series classification.

Submission Number: 126