Stochastic Sparse Sampling: A Variable-Length Time Series Classification Framework for Seizure Onset Zone Localization
Bibliographic record
Abstract
Variable-length time series classification (VTSC) problems are prevalent in healthcare applications, such as heart rate monitoring and electrophysiological recordings, where sequence length varies among patients and events. VTSC is challenging as finite-context models such as Transformers require padding, truncation, or interpolation, leading to distortion in the input data, higher computational costs, and overfitting, while infinite-context models including recurrent neural networks struggle with overcompression and unstable gradients over long sequences. In this paper, we develop a novel VTSC framework based on Stochastic Sparse Sampling (SSS) for seizure onset zone (SOZ) localization, a critical VTSC problem requiring identification of seizure-inducing brain regions from variable-length electrophysiological time series. The proposed framework sparsely samples time series windows to compute local predictions, which are then aggregated and calibrated to form a global prediction. SSS provides post-hoc insights into local signal characteristics related to the SOZ, by visualizing temporally averaged local predictions throughout the signal. We evaluate our method on the Epilepsy intracranial electroencephalography (iEEG) Multicenter Dataset, a heterogeneous collection of iEEG recordings obtained from four independent medical centers. The proposed solution outperforms state-of-the-art (SOTA) baselines across most medical centers, and superior performance on all out-of- distribution (OOD) unseen medical centers.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".