TabNSM: Neural Sparse Mixer for Tabular Regression
Authors: Ali Eslamian, Qiang Cheng
Organizations: Department of Computer Science University of Kentucky Lexington, KY 40506 · Department of Computer Science Institute for Biomedical Informatics University of Kentucky Lexington, KY 40506
Large-scale, high-dimensional tabular regression remains challenging: tree-based models are robust but lack end-to-end representation learning, while deep models enable flexible feature learning but often incur costly interaction modeling and sensitivity to noisy or redundant features. We propose TabNSM, a scalable regression framework that extends our earlier sparse-attention and mixer architectures. At its core, the Adaptive Sparse Interaction Module (ASIM) integrates foreground feature discovery, sparse local interaction encoding, and Feature-Token Mixing, providing near-linear complexity under fixed sparse configurations. For regression, TabNSM introduces three complementary components: a Multi-Stage Regression Head for progressive prediction refinement; GridLoss, an ordinal-aware soft-binning objective that incorporates target structure into representation learning; and RISE (Reweighted Instance Sampling by Error), a difficulty-aware sampling strategy based on loss-quantile bins. Across nine real-world regression benchmarks, TabNSM delivers strong predictive performance and practical scalability, with particularly consistent gains on high-dimensional and heterogeneous datasets. These results demonstrate that selective interaction modeling, structured regression supervision, and difficulty-aware sampling provide an effective and scalable approach to deep tabular regression.
Figures & tables
Figure 1: Overview of the TabNSM architecture. TabNSM extends the published TabNSA–TabMixer representation backbone with regression-specific residual integration and a Multi-Stage Regression Head. Within ASIM, the inherited structured sparse-attention operator provides instance-adaptive feature selection, while the inherited FTM operator propagates broader feature-level context. Learnable residual blending couples these streams, and the resulting representation is passed to progressively narrowed MLP branches with residual coupling and final feature fusion to produce y^ .
Model
SA
CP
AQ
TO
SC
CD
ChD
EVP
RES
Best Classical (6 models)
0.175
3.719
12.816
0.027
3.602
0.236
8717
26.104
3163
Best Tree-based (5 models)
0.171
2.617
5.869
0.027
3.455
0.004
17525
2.799
3135
Best MLP-style (5 models)
0.167
2.920
4.578
0.028
3.920
0.028
4963
1.556
3161
Best Transformer (6 models)
0.156
2.901
4.081
0.028
3.667
0.007
4475
1.507
3163
Best Retrieval (4 models)
0.150
2.833
5.062
0.028
3.454
0.052
22661
2.653
3187
Best Other (8 models)
0.149
2.991
4.690
0.028
3.570
0.136
4808
3.219
3163
Table 1: RMSE on nine regression benchmarks. Lower is better. Best results are shown in bold , and second-best results are underlined . We report the best-performing baseline within each model family; full per-model results are provided in Appendix C.1 .
Figure 2: Ablation and scalability analyses. (a) Full attention, Mamba, and ASIM within TabNSM; ASIM achieves the lowest RMSE. (b) Parameter count grows approximately linearly with retained feature fraction, consistent with the ASIM complexity analysis.
Appendix figures & tables20 assets
Supplementary material from the paper’s appendix.
Appendix
Model
SA
CP
AQ
TO
SC
CD
ChD
EVP
RES
Classical
LinearRegression
0.402
9.277
15.062
0.028
3.997
0.236
8717.544
35.156
3163
KNN-5
0.238
3.719
12.816
0.029
3.602
1.347
15860.523
26.104
3212
Lasso
0.402
9.277
15.064
0.028
3.964
0.251
8717.439
35.155
3163
Ridge
0.402
9.277
15.062
0.027
3.982
0.236
8717.479
35.156
3163
SVR-Linear
0.406
11.663
17.854
0.042
3.974
♢,†
♢,†
♢,†
♢,†
SVR-RBF
0.175
7.491
19.416
0.038
3.964
∗
∗
∗
∗
Appendix
Table 2: Evaluation of different models on regression tasks. Results report RMSE (lower is better).
Figure 3: Critical Difference diagram (Nemenyi post-hoc test, α=0.05 ). Each dot is a model coloured by architectural family; its horizontal position is its average rank across five benchmarks (lower = better). The CD bracket shows the minimum rank difference required for statistical significance (CD = 26.8). Models marked with + (GrowNet, SVR-Linear) fall outside TabNSM’s critical difference band and are significantly worse. The large CD is expected when k≫N ; the Friedman test nonetheless confirms a significant overall difference ( p=4.25×10−5 ).
Figure 4: Average rank across nine benchmarks for each model (lower is better), coloured by architectural family. All baselines are statistically significantly worse than TabNSM (one-sided Wilcoxon signed-rank test, Benjamini–Hochberg corrected [ Benjamini and Hochberg, 1995 ] , α=0.05 ; all corrected p≤0.02 ). Missing values are imputed as worst rank.
Figure 5: Per-instance feature attribution heatmap for TabNSM. Each row corresponds to a test instance and each column corresponds to an input feature. Cell intensity represents the normalized attribution score, computed using gradient–embedding attribution and scaled to [0,1] within each instance. Brighter cells indicate features with stronger influence on the prediction. The sparse and instance-varying attribution patterns suggest that TabNSM adaptively focuses on different feature subsets across samples.
Figure 6: Sensitivity analysis with respect to random seed initialization. The boxplot shows the distribution of test Root Mean Squared Error (RMSE) over 20 independent runs with different random seeds. Boxes indicate the interquartile range (IQR), the center line denotes the median, and whiskers extend to 1.5×IQR . Lower values indicate better performance.
Dataset
n
d
CatBoost Time (s)
TabNSM Time (s)
cpu
8,192
12
1.042
0.346
topo
8,885
266
10.788
0.333
sarcos
48,933
27
2.111
0.333
EVP
264,628
392
14.986
0.346
ChD
309,215
405
17.252
0.349
CD
1,004,991
401
45.476
0.398
Appendix
Table 5: Runtime in seconds for CatBoost and TabNSM under the validation-loss threshold protocol. Lower is better. CatBoost is evaluated on CPU, whereas TabNSM uses GPU acceleration.
Dataset
CatBoost
TabNSM
EVP
N/A
477
ChD
N/A
529
CD
N/A
1621
Appendix
Table 6: Peak GPU memory usage in MB for TabNSM. CatBoost is run on CPU, so GPU memory is not applicable.
Dataset
CatBoost
TabNSM
EVP
3763.77
3006.73
ChD
4325.94
3408.70
CD
12080.61
8524.16
Appendix
Table 7: CPU memory increase in MB during training. Lower is better.
Figure 7: Training time versus sample size. Runtime is measured under the validation-loss threshold protocol. CatBoost runtime increases with dataset size, whereas TabNSM maintains low runtime across the evaluated settings, reflecting mini-batch GPU training and sparse feature interaction modeling.
Figure 8: Accuracy–efficiency trade-off for tabular learning methods. The figure summarizes predictive accuracy and computational efficiency across representative tabular learning models.
CP
TO
SA
EVP
w/o FTM
3.966
0.034
0.176
570.09
Full TabNSM
2.842
0.021
0.137
1.199
Appendix
Table 8: Ablation of the FTM pathway. Lower RMSE is better.
Figure 9: Loss-function ablation across three datasets. RMSE is reported on a log scale. Values above bars indicate relative change with respect to GridLoss. GridLoss achieves the lowest or comparable RMSE across the evaluated datasets, while pointwise losses such as MAE and LogCosh can degrade substantially in high-error regimes.
Figure 10: Final validation metric distributions across multiple runs for models trained with and without RISE.
Figure 11: Sensitivity to feature dimensionality and sample size. The top panel evaluates robustness under varying numbers of retained input features, while the bottom panel evaluates robustness under varying fractions of training samples. Separate y-axes are used to accommodate differences in error scale.
Dataset
Std
IQR
IQR/Std
Tail Type
Preferred τ
RMSE– τ Behavior
CP
18.40
13.00
0.71
Heavy-tailed
Large
Monotonic decrease
TO
0.03
0.02
0.67
Rare extremes
Small
Sharp peak
SCAN-2
4.99
0.00
0.00
Degenerate bulk
Very small
Highly non-monotonic
Appendix
Table 9: Target distribution statistics and their relationship to τ sensitivity.
Figure 12: Normalized RMSE as a function of τ across datasets.
Figure 13: Normalized RMSE as a function of α across datasets.
Figure 14: Component-wise ablation of sparse attention parameters. Each plot shows the effect of varying one parameter: number_of_selected_blocks (top-left), selection_block_size (top-right), compress_block_size (bottom-left), and sliding_window_size (bottom-right) on the average validation RMSE across four datasets.