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arXiv 1907.04529stat.ME
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回归Copula函数的贝叶斯推断

Bayesian Inference for Regression Copulas

Michael Stanley Smith, Nadja Klein

摘要:

我们提出了一个新的半参数分布回归平滑,是基于Copula分解的联合分布的响应值的向量。Copula是高维的,通过伪回归的反演来构造,其中条件均值和方差是使用正则化基函数建模的协变量的半参数函数。通过对基系数进行积分,得到协变量空间上的隐式copula过程,我们称之为“回归copula”。我们将其与非参数边际相结合来定义Copula模型,其中响应的整个分布(包括均值和方差)是协变量的光滑半参数函数。Copula估计使用哈密顿蒙特卡罗和变分贝叶斯,后者是可扩展到高维。使用真实数据的例子和模拟研究,我们说明了这些估计和copula模型的有效性。在一个实质性的例子中,我们估计半小时电力现货价格的分布作为需求和两个时间协变量的函数,使用径向基和马蹄正则化。Copula模型产生的分布估计是局部自适应的协变量,预测比基准模型更准确。

英文摘要:

We propose a new semi-parametric distributional regression smoother that is based on a copula decomposition of the joint distribution of the vector of response values. The copula is high-dimensional and constructed by inversion of a pseudo regression, where the conditional mean and variance are semi-parametric functions of covariates modeled using regularized basis functions. By integrating out the basis coefficients, an implicit copula process on the covariate space is obtained, which we call a `regression copula'. We combine this with a non-parametric margin to define a copula model, where the entire distribution - including the mean and variance - of the response is a smooth semi-parametric function of the covariates. The copula is estimated using both Hamiltonian Monte Carlo and variational Bayes; the latter of which is scalable to high dimensions. Using real data examples and a simulation study we illustrate the efficacy of these estimators and the copula model. In a substantive example, we estimate the distribution of half-hourly electricity spot prices as a function of demand and two time covariates using radial bases and horseshoe regularization. The copula model produces distributional estimates that are locally adaptive with respect to the covariates, and predictions that are more accurate than those from benchmark models.

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