arXiv Statistics ML

Scale-invariant Optimal Sampling for Rare-events Data with Sparse Models

arXiv Machine Learning
Oct 21

Fixed-Size Active Statistical Inference

The paper introduces Conditional Poisson Sampling (CPS) as a fixed-size alternative to Poisson Sampling (PS) for variance reduction in statistical inference. CPS can replace PS in multivariate Z-estimation problems, including convex M-estimation, without increasing asymptotic variance and often improving it when predictions are imperfect. The authors demonstrate these benefits on synthetic and real datasets and provide a Python package for CPS implementation.

By Erik Skalnes, Michael Oberst
arXiv Statistics ML
5d ago

Unifying Sparse Estimation of Precision and Covariance Matrices

The paper proposes a unified framework for estimating sparse precision and covariance matrices by reparametrizing the last column of either matrix. This reparametrization reduces the likelihood optimization to a one‑dimensional minimization followed by a penalized multiple regression, applicable to any penalty separable in off‑diagonal entries and linear on the diagonal. When the penalty is the α1 norm, the method simultaneously recovers the graphical Lasso and the covariance graphical Lasso algorithms.

By Aramayis Dallakyan, Mohsen Pourahmadi
arXiv Machine Learning
Aug 19

Online Generalized Sparse Regression: How Does Overparametrization Help?

The paper introduces an online generalized-sparsity-constrained regression framework that addresses key challenges in online sparse regression, such as dynamic regularization, memory usage, and real-time computation. It proposes an efficient online hard‑thresholding algorithm that performs closed‑form updates using only summary statistics, achieving global convergence at optimal statistical rates when the projection set is overparameterized. Numerical experiments show the method consistently outperforms existing alternatives in online cardinality‑constrained linear regression and low‑rank matrix sensing.

By Shuoguang Yang, Qiang Sun
arXiv Statistics ML
Oct 19

Cointegrated Regressors: Where Folded Concave Penalties Go Beyond LASSO

The paper discusses the limitations of LASSO in high‑dimensional regression models when cointegrated regressors are present, noting that the convex penalty can overly shrink their coefficients and lead to inconsistent estimation. It proposes using folded concave penalties (FCP), such as SCAD and MCP, to overcome this issue, establishing both local and global oracle properties for the penalized regression. Simulation results and an application to euro area unemployment forecasting demonstrate that FCP improves variable selection and out‑of‑sample prediction compared to LASSO.

By Hongqi Chen, Chengwang Liao, Ziwei Mei, Zhentao Shi