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Alexej Gossmann

6 accepted papers

2025

"Who experiences large model decay and why?" A Hierarchical Framework for Diagnosing Heterogeneous Performance Drift

ICML 2025poster

Machine learning (ML) models frequently experience performance degradation when deployed in new contexts. Such degradation is rarely uniform: some subgroups may suffer large performance decay while others may not. Understanding where and how large differences in performance arise is critical for des…

Cited by 0SourcePDFScholar
2025

M-HOF-Opt: Multi-Objective Hierarchical Output Feedback Optimization via Multiplier Induced Loss Landscape Scheduling

AISTATS 2025poster

A probabilistic graphical model is proposed, modeling the joint model parameter and multiplier evolution, with a hypervolume based likelihood, promoting multi-objective descent in structural risk minimization. We address multi-objective model parameter optimization via a surrogate single objective…

Cited by 0SourcecodeScholar
2024

A hierarchical decomposition for explaining ML performance discrepancies

NeurIPS 2024poster

Machine learning (ML) algorithms can often differ in performance across domains. Understanding why their performance differs is crucial for determining what types of interventions (e.g., algorithmic or operational) are most effective at closing the performance gaps. Aggregate decompositions express…

Cited by 2SourcePDFScholar
2024

Is this model reliable for everyone? Testing for strong calibration

AISTATS 2024poster

In a well-calibrated risk prediction model, the average predicted probability is close to the true event rate for any given subgroup. Such models are reliable across heterogeneous populations and satisfy strong notions of algorithmic fairness. However, the task of auditing a model for strong calibra…

2024

Monitoring machine learning-based risk prediction algorithms in the presence of performativity

AISTATS 2024poster

Performance monitoring of machine learning (ML)-based risk prediction models in healthcare is complicated by the issue of performativity: when an algorithm predicts a patient to be at high risk for an adverse event, clinicians are more likely to administer prophylactic treatment and alter the very t…

Cited by 8SourcePDFScholar
2022

Sequential algorithmic modification with test data reuse

UAI 2022poster

After initial release of a machine learning algorithm, the model can be fine-tuned by retraining on subsequently gathered data, adding newly discovered features, or more. Each modification introduces a risk of deteriorating performance and must be validated on a test dataset. It may not always be pr…