论文标题
确定的桥梁回归
SURE-tuned Bridge Regression
论文作者
论文摘要
考虑{$ \ell_α$}正规化线性回归,也称为桥梁回归。对于$α\在(0,1)$中,桥梁回归享有一些感兴趣的统计属性,例如估计值的稀疏性和几乎不稳定性(Fan and Li,2001)。但是,主要困难在于这些值$α$的罚款的非凸性性质,这使优化程序具有挑战性,通常只能找到局部最佳。为了解决这个问题,Polson等。 (2013年)使用桥梁惩罚与回归系数上的功率指数先验之间的对应关系,采用了基于抽样的完全贝叶斯方法来解决此问题。但是,它们的抽样过程依赖于马尔可夫链蒙特卡洛(MCMC)技术,这些技术本质上是顺序的,不可扩展到大问题维度。交叉验证方法类似地是计算密集型的。为此,我们的贡献是适合桥梁回归模型的新颖\ emph {非著作}方法。主要贡献是针对Stein对桥梁回归的未偏见预测风险的明确公式,然后可以对其进行优化以选择所需的调整参数,从而使我们能够完全绕过MCMC以及计算强度的交叉验证方法。与迭代方案相比,我们的程序产生的计算时间很少,而统计绩效没有任何明显的损失。 R实现将在线公开,网址为:https://github.com/loriaj/sure-tuned_bridgeregression。
Consider the {$\ell_α$} regularized linear regression, also termed Bridge regression. For $α\in (0,1)$, Bridge regression enjoys several statistical properties of interest such as sparsity and near-unbiasedness of the estimates (Fan and Li, 2001). However, the main difficulty lies in the non-convex nature of the penalty for these values of $α$, which makes an optimization procedure challenging and usually it is only possible to find a local optimum. To address this issue, Polson et al. (2013) took a sampling based fully Bayesian approach to this problem, using the correspondence between the Bridge penalty and a power exponential prior on the regression coefficients. However, their sampling procedure relies on Markov chain Monte Carlo (MCMC) techniques, which are inherently sequential and not scalable to large problem dimensions. Cross validation approaches are similarly computation-intensive. To this end, our contribution is a novel \emph{non-iterative} method to fit a Bridge regression model. The main contribution lies in an explicit formula for Stein's unbiased risk estimate for the out of sample prediction risk of Bridge regression, which can then be optimized to select the desired tuning parameters, allowing us to completely bypass MCMC as well as computation-intensive cross validation approaches. Our procedure yields results in a fraction of computational times compared to iterative schemes, without any appreciable loss in statistical performance. An R implementation is publicly available online at: https://github.com/loriaJ/Sure-tuned_BridgeRegression .