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About this paper

Bariscan Bozkurt, Ben Deaner, Dimitri Meunier, Liyuan Xu, Arthur Gretton

The paper presents proxy causal learning for estimating treatment effects when a confounder is hidden and treatment and outcome proxies are observed. It constructs a treatment bridge with kernel ridge regression, avoiding explicit density-ratio estimation. On dSprite’s 4,096-dimensional treatments, error is lower than Kernel Negative Control and comparable to KPV and PMMR, under stated identification assumptions.

Key insights

  • The least-squares objective for the treatment bridge function can be algebraically simplified to eliminate the need for explicit density ratio estimation.
  • Utilizing Reproducing Kernel Hilbert Spaces enables the derivation of closed-form solutions for causal effect estimators through multi-stage kernel ridge regression, enhancing computational tractability.
  • Ablation studies reveal that treatment bridge methods can perform better when the outcome proxy is more informative, while outcome bridge methods benefit from a more informative treatment proxy, suggesting complementary strengths.

Summary by alphaXiv.

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