2026

Explaining Tabular Foundation Model Differences Through Meta-Features

Markus Herre, Andrej Tschalzev, Sascha Marton, Christian Bartelt

2nd ICML Workshop on Foundation Models for Structured Data (2026)

With the rise of tabular foundation models alongside traditional models still performing well on many tasks, choosing the right model for a tabular dataset remains difficult. We investigate whether dataset meta-features can explain performance gaps between model families on tabular prediction tasks. Using the TabArena benchmark results, we analyze dataset-level performance gaps and relate them to model-agnostic meta-features. After strict statistical tests with false discovery control, we find that (1) for neural network vs. tree gaps, no meta-feature survives false discovery control, (2) for non-foundation vs. foundation model gaps, one association is robust but does not generalize when tested in leave-one-dataset-out prediction, and (3) for TabICLv2 vs. TabPFN-2.6, one robust association also improves held-out prediction. Furthermore, we conduct a leave-one-dataset-out analysis and find that meta-feature predictors fail to improve meaningfully over a simple baseline. Overall, our results show the heterogeneity of tabular datasets and that global meta-feature approaches are not robust enough to offer explanations on the 51 TabArena datasets.

Figure 1: Two panels comparing TabICLv2 and TabPFN-2.6. Left, ROC AUC vs. total feature count d: both models track together until d grows large, where TabICLv2 drops sharply while TabPFN-2.6 stays flat. Right, the TabICLv2-minus-TabPFN AUC gap as a function of redundant nuisance fraction: many independent columns favor TabPFN, but converting them into redundant copies closes the gap toward zero.
Meta-feature analysis on TabArena: TabICLv2 vs. TabPFN-2.6 across total feature count (left) and redundant-feature fraction (right).

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