ReTabSyn: Realistic Tabular Data Synthesis via Reinforcement Learning
Organizations: University of California, Los Angeles, USA · University of South Florida, USA · Cisco, USA · University of Mississippi, USA
Abstract
Deep generative models can help with data scarcity and privacy by producing synthetic training data, but they struggle in low-data, imbalanced tabular settings to fully learn the complex data distribution. We argue that striving for the full joint distribution could be overkill; for greater data efficiency, models should prioritize learning the conditional distribution , as suggested by recent theoretical analysis. Therefore, we overcome this limitation with ReTabSyn, a Reinforced Tabular Synthesis pipeline that provides direct feedback on feature correlation preservation during synthesizer training. This objective encourages the generator to prioritize the most useful predictive signals when training data is limited, thereby strengthening downstream model utility. We empirically fine-tune a language model-based generator using this approach, and across benchmarks with small sample sizes, class imbalance, and distribution shift, ReTabSyn consistently outperforms state-of-the-art baselines. Moreover, our approach can be readily extended to control various aspects of synthetic tabular data, such as applying expert-specified constraints on generated observations.
Figures & tables
| Dataset | Rows | Num Cols | Cate Cols |
|---|---|---|---|
| Adult | 48,812 | 6 | 8 |
| Bean | 13,611 | 16 | 1 |
| Churn-Modelling | 10,000 | 6 | 4 |
| HTRU2 | 17,898 | 8 | 1 |
| Indian Liver Patient | 579 | 9 | 2 |
| Obesity | 2,111 | 8 | 9 |
| Model | Adult | Churn | HTRU2 | Magic | Shoppers |
|---|---|---|---|---|---|
| Real | |||||
| TVAE | |||||
| GReaT | |||||
| SMOTE | |||||
| TabSyn | |||||
| SynRL |
| Model | Adult | Churn | Liver | Titanic |
|---|---|---|---|---|
| Real | ||||
| TVAE | ||||
| GReaT | ||||
| SMOTE | ||||
| TabSyn | ||||
| SynRL |
| Model | Precision | Recall | Shape | Corr. |
|---|---|---|---|---|
| TVAE | ||||
| SMOTE | ||||
| TabSyn | ||||
| GReaT | ||||
| SynRL | ||||
| PTA |
| Model | AUC | TPR@FPR=0.01 | Authenticity |
|---|---|---|---|
| TVAE | |||
| SMOTE | |||
| TabSyn | |||
| GReaT | |||
| SynRL | |||
| PTA |
| AUROC | Corr. | Prec. | Recall | |
| Default ReTabSyn | 0.841 | 0.880 | 0.763 | 0.471 |
| Training stages | ||||
| Only DPO (no aug.) | 0.800 | 0.810 | 0.713 | 0.429 |
| Only Aug. pre-train | 0.815 | 0.851 | 0.749 | 0.420 |
| Reward supervision (§ 3.3 ) | ||||
| Oracle editing | 0.809 | 0.867 | 0.731 | 0.427 |
Appendix figures & tables16 assets
Supplementary material from the paper’s appendix.
Appendix
| Dataset Name | Split Column | Train / Test Composition | N Train | N Test |
| Adult | native-country | United States / non-US | 43,152 | 5,128 |
| Indian liver patient | Gender | Male / Female | 441 | 142 |
| Obesity | Gender | Male / Female | 1068 | 1043 |
| Churn Modeling | Country | France & Germany / Spain | 7,519 | 2,477 |
| Titanic | Sex | Male / Female | 577 | 314 |
| Attack | Threat model | Signal type |
|---|---|---|
| DOMIAS ( van Breugel et al., 2023 ) | Shadow-box | Density ratio |
| DPI ( Ward et al., 2024 ) | Shadow-box | Local density |
| Classifier ( Houssiau et al., 2022 ) | Shadow-box | Density ratio |
| Density Estimator ( Houssiau et al., 2022 ) | Black-box | Density estimation |
| DCR ( Chen et al., 2020 ) | Black-box | Distance-based |
| DCR-Diff ( Chen et al., 2020 ) | Shadow-box | Distance difference |
| Model | Train | Fine‑tune | Sampling |
|---|---|---|---|
| ReTabSyn | 1hrs | 3mins | 7mins |
| GReaT | 1hrs | - | 7mins |
| TabSyn | 55mins | - | 2mins |
| SMOTE | - | - | 3mins |
| Model | Hyperparameter | Values |
|---|---|---|
| XGBoost | n_estimators | {50, 100, 200} |
| max_depth | {3, 4, 5} | |
| learning_rate | {0.01, 0.1, 0.2} | |
| CatBoost | iterations | {100, 200, 500} |
| depth | {4, 6, 8} | |
| learning_rate | {0.01, 0.05, 0.1} |
| Model | I1 | I2 | I3 |
|---|---|---|---|
| SMOTE | 3.28% | 2.13% | 2.73% |
| TabSyn | 1.02% | 1.22% | 2.00% |
| GReaT | 1.00% | 1.20% | 2.00% |
| ReTabSyn | 0.00% | 0.00% | 0.00% |
| Model | Abalone | Insurance | Shoppers |
|---|---|---|---|
| Real | 0.291 | 0.714 | 0.201 |
| SMOTE | 0.250 | 0.690 | 0.190 |
| TabSyn | 0.170 | 0.200 | 0.010 |
| GReaT | 0.123 | -1.417 | -0.058 |
| ReTabSyn | 0.191 | 0.226 | 0.093 |
| Dataset | § 4.3 (imbalance) | § 4.4 (shift) |
|---|---|---|
| Adult | eligible | eligible |
| Bean | multi-class | no demo/geo column |
| Churn | eligible | eligible |
| HTRU2 | eligible | no demo/geo column |
| ILP | low support @1% | eligible |
| Magic | eligible | no demo/geo column |
| Size | Real | GReaT | SMOTE | TabSyn | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|---|
| 32 | ||||||||
| 64 | ||||||||
| 128 | ||||||||
| 256 | ||||||||
| 512 |
| Wilt | Churn | |||||
|---|---|---|---|---|---|---|
| Method | AUROC | Prec. | Recall | AUROC | Prec. | Recall |
| Real data | ||||||
| SMOTE | ||||||
| Qwen3.5 Pretrain | ||||||
| Qwen3.5 + ReTabSyn | ||||||
| GPT-5.4 (prompted) | ||||||
| Metric | SMOTE | GReaT | TabSyn | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|
| Mean AUROC (alternative) | 0.678 | 0.655 | 0.663 | 0.685 | 0.646 | 0.652 | 0.673 |
| Mean AUROC (default) | 0.744 | 0.731 | 0.730 | 0.756 | 0.711 | 0.718 | 0.740 |
| Wins (alternative) | 2/12 | 1/12 | 1/12 | 8/12 | 0/12 | 0/12 | 0/12 |
| Target Column | Real | SMOTE | GReaT | TabSyn | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|---|
| Exited (default) | ||||||||
| Geography | ||||||||
| Gender | ||||||||
| IsActiveMember | ||||||||
| HasCrCard |
| Target Column | Real | SMOTE | GReaT | TabSyn | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|---|
| NObeyesdad (default) | ||||||||
| Gender | ||||||||
| FAVC | ||||||||
| CAEC | ||||||||
| family_history |
| Target Column | Real | SMOTE | GReaT | TabSyn | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|---|
| Survived (default) | ||||||||
| Sex | ||||||||
| Pclass | ||||||||
| Embarked |
| Target Column | Real | SMOTE | GReaT | TabSyn | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|---|
| Dataset (default) | ||||||||
| Gender |
| Setting | Real | SMOTE | GReaT | ReTabSyn | TVAE | SynRL | PTA |
|---|---|---|---|---|---|---|---|
| Adult, synth | 0.853 | ||||||
| Adult, augmented | 0.853 | ||||||
| Magic, synth | 0.884 | ||||||
| Magic, augmented | 0.884 |
| 0.05 | 0.1 | 0.2 | |
|---|---|---|---|
| AUROC | 0.837 | 0.841 | 0.839 |
| 0 | 0.1 | 0.2 | |
| AUROC | 0.772 | 0.841 | 0.822 |
Synthetic Tabular Data Generation
Synthetic tabular data generation creates artificial records that preserve useful feature relationships while limiting exposure of sensitive data.
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