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arXiv 1604.01992math.STstat.TH
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相依情形下的自适应非参数工具回归

Adaptive non-parametric instrumental regression in the presence of dependence

Nicolas Asin, Jan Johannes

摘要:

我们考虑估计的结构函数模型的响应和内源性回归之间的非参数关系给定的工具在数据生成过程中存在的依赖。假设一个独立同分布(IID.)Johannes和Schwarz(2010)已经表明,基于降维和阈值的最小二乘估计器可以达到最小最大最优收敛速率,直到常数。由于这种估计过程需要对未知结构函数的某些特性进行维数参数的最佳选择,因此我们基于模型选择和Goldenshluger和Lepski(2011)启发的Lepski方法的组合来研究其完全数据驱动的选择。对于由此产生的完全数据驱动的阈值最小二乘估计的非渐近预言风险界,通过考虑一个iid。或者说,是放弃了独立性假设。在这两种情况下,假设依赖性足够弱,特征是混合系数快速衰减,则推导出的风险界限一致,直至达到常数。利用风险界证明了估计量的极大极小最优性。

英文摘要:

We consider the estimation of a structural function which models a non-parametric relationship between a response and an endogenous regressor given an instrument in presence of dependence in the data generating process. Assuming an independent and identically distributed (iid.) sample it has been shown in Johannes and Schwarz (2010) that a least squares estimator based on dimension reduction and thresholding can attain minimax-optimal rates of convergence up to a constant. As this estimation procedure requires an optimal choice of a dimension parameter with regard amongst others to certain characteristics of the unknown structural function we investigate its fully data-driven choice based on a combination of model selection and Lepski's method inspired by Goldenshluger and Lepski (2011). For the resulting fully data-driven thresholded least squares estimator a non-asymptotic oracle risk bound is derived by considering either an iid. sample or by dismissing the independence assumption. In both cases the derived risk bounds coincide up to a constant assuming sufficiently weak dependence characterised by a fast decay of the mixing coefficients. Employing the risk bounds the minimax optimality up to constant of the estimator is established over a variety of classes of structural functions.

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