通过融入因果结构,提升TabPFN生成合成表格数据的质量与稳定性。
Improving TabPFN's Synthetic Data Generation by Integrating Causal Structure
- 用因果图指导特征生成顺序,避免因序列入侵导致虚假相关。
- 在六大数据集上,新方法显著改善了数据分布与处理效应的保真度。
- 无需重训练,仅在推理时注入因果信息即可生效,适合有领域知识的研究者。
合成表格数据生成可缓解多个领域的数据稀缺与隐私问题。最近提出的表格式先验拟合网络(TabPFN)已被证明能生成高质量的合成表格数据。然而,TabPFN采用自回归方式生成:特征按输入数据中的顺序逐个生成,依赖于前序特征的条件。我们发现,当特征顺序与因果结构冲突时,模型会产生虚假相关,影响合成数据质量并破坏因果效应。为此,我们通过两种互补策略将因果结构融入TabPFN的生成过程:一是基于有向无环图(DAG)的条件采样,即按因果父节点生成变量;二是部分有向无环图(PDAG)策略,适用于因果知识不完全的情况。我们在受控基准和六个CSuite数据集上评估了这些方法,指标包括结构保真度、分布质量及平均处理效应(ATE)保留率。结果显示,在多数场景下,基于DAG的条件化显著提升了合成数据的质量与稳定性。在部分因果知识下,已知的完整部分有向无环图(oracle-PDAG)带来适度改进,而从数据中学习的完整部分有向无环图(CPDAG)效果取决于因果结构恢复程度。结果表明,即使仅有部分可靠的因果结构,也可在不更新参数的情况下,于推理阶段注入以提升合成数据质量。
原文摘要 · Abstract (English)
Synthetic tabular data generation addresses data scarcity and privacy constraints in a variety of domains. Tabular Prior-Data Fitted Network (TabPFN), a recent foundation model for tabular data, has been shown capable of generating high-quality synthetic tabular data. However, TabPFN is autoregressive: features are generated sequentially by conditioning on the previous ones, depending on the order in which they appear in the input data. We demonstrate that when the feature order conflicts with causal structure, the model produces spurious correlations that impair its ability to generate synthetic data and preserve causal effects. We address this limitation by integrating causal structure into TabPFN's generation process through two complementary approaches: Directed Acyclic Graph (DAG)-aware conditioning, which samples each variable given its causal parents, and a partially directed acyclic graph (PDAG)-based strategy for scenarios with partial causal knowledge. We evaluate these approaches on controlled benchmarks and six CSuite datasets, assessing structural fidelity, distributional quality, and Average Treatment Effect (ATE) preservation. Across most settings, DAG-aware conditioning improves the quality and stability of synthetic data relative to vanilla TabPFN. Under partial causal knowledge, the oracle partially directed acyclic graph (oracle-PDAG), which orients only the edges into the colliders, shows moderate gains, while the benefit of a Completed Partially Directed Acyclic Graph (CPDAG) discovered from data depends on how well the causal structure is recovered. These results indicate that reliable causal structure, even partial, can be injected into TabPFN at inference time, without parameter updates, to improve synthetic data quality.
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