Cho Brian, Mukhin Yaroslav, Gan Kyra, Malenica Ivana
Department of ORIE, Cornell Tech, NY, USA.
Massachusetts Institute of Technology, Cambridge, MA, USA.
Proc Mach Learn Res. 2024 Jul;235:8534-8555.
When estimating target parameters in nonparametric models with nuisance parameters, substituting the unknown nuisances with nonparametric estimators can introduce "plug-in bias." Traditional methods addressing this suboptimal bias-variance trade-off rely on the (IF) of the target parameter. When estimating multiple target parameters, these methods require debiasing the nuisance parameter multiple times using the corresponding IFs, which poses analytical and computational challenges. In this work, we leverage the (TMLE) framework to propose a novel method named (KDPE). KDPE refines an initial estimate through regularized likelihood maximization steps, employing a nonparametric model based on . We show that KDPE: (i) simultaneously debiases pathwise differentiable target parameters that satisfy our regularity conditions, (ii) does not require the IF for implementation, and (iii) remains computationally tractable. We numerically illustrate the use of KDPE and validate our theoretical results.
在具有干扰参数的非参数模型中估计目标参数时,用非参数估计器替代未知干扰会引入“插入偏差”。解决这种次优偏差 - 方差权衡的传统方法依赖于目标参数的影响函数(IF)。在估计多个目标参数时,这些方法需要使用相应的影响函数对干扰参数进行多次去偏,这带来了分析和计算上的挑战。在这项工作中,我们利用全有效最大似然估计(TMLE)框架提出了一种名为核密度路径估计(KDPE)的新方法。KDPE通过正则化似然最大化步骤改进初始估计,采用基于核密度的非参数模型。我们证明KDPE:(i)同时对满足我们正则性条件的逐路径可微目标参数进行去偏,(ii)实施时不需要影响函数,(iii)在计算上仍然易于处理。我们通过数值示例说明了KDPE的使用并验证了我们的理论结果。