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Sifan Liu

Assistant Professor of Statistical Science
Statistical Science

Selected Publications


Selective Inference with Distributed Data

Journal Article Journal of Machine Learning Research · January 1, 2025 When data are distributed across multiple sites or machines rather than centralized in one location, researchers face the challenge of extracting meaningful information without directly sharing individual data points. While there are many distributed metho ... Cite

CONDITIONAL QUASI-MONTE CARLO WITH CONSTRAINED ACTIVE SUBSPACES

Journal Article SIAM Journal on Scientific Computing · October 1, 2024 Conditional Monte Carlo or pre-integration is a powerful tool for reducing variance and improving the regularity of integrands when using Monte Carlo and quasi-Monte Carlo (QMC) methods. To select the variable to pre-integrate, one must consider both the v ... Full text Cite

PREINTEGRATION VIA ACTIVE SUBSPACE

Journal Article SIAM Journal on Numerical Analysis · January 1, 2023 Preintegration is an extension of conditional Monte Carlo to quasi-Monte Carlo and randomized quasi-Monte Carlo. Conditioning can reduce but not increase the variance in Monte Carlo. For quasi-Monte Carlo it can bring about improved regularity of the integ ... Full text Cite

Langevin Quasi-Monte Carlo

Conference Advances in Neural Information Processing Systems · January 1, 2023 Langevin Monte Carlo (LMC) and its stochastic gradient versions are powerful algorithms for sampling from complex high-dimensional distributions. To sample from a distribution with density π(θ) ∝ exp(−U(θ)), LMC iteratively generates the next sample by tak ... Cite

GLOBAL AND INDIVIDUALIZED COMMUNITY DETECTION IN INHOMOGENEOUS MULTILAYER NETWORKS

Journal Article Annals of Statistics · October 1, 2022 In network applications, it has become increasingly common to obtain datasets in the form of multiple networks observed on the same set of subjects, where each network is obtained in a related but different experiment condition or application scenario. Suc ... Full text Cite

Statistical Challenges in Tracking the Evolution of SARS-CoV-2

Journal Article Statistical Science · May 1, 2022 Genomic surveillance of SARS-CoV-2 has been instrumental in tracking the spread and evolution of the virus during the pandemic. The availability of SARS-CoV-2 molecular sequences isolated from infected individuals, coupled with phylodynamic methods, have p ... Full text Cite

How to Reduce Dimension with PCA and Random Projections?

Journal Article IEEE Transactions on Information Theory · December 1, 2021 In our 'big data' age, the size and complexity of data is steadily increasing. Methods for dimension reduction are ever more popular and useful. Two distinct types of dimension reduction are 'data-oblivious' methods such as random projections and sketching ... Full text Cite

Quasi-Monte Carlo quasi-Newton in variational bayes

Journal Article Journal of Machine Learning Research · January 1, 2021 Many machine learning problems optimize an objective that must be measured with noise. The primary method is a first order stochastic gradient descent using one or more Monte Carlo (MC) samples at each step. There are settings where ill-conditioning makes ... Cite

RIDGE REGRESSION: STRUCTURE, CROSS-VALIDATION, AND SKETCHING

Conference 8th International Conference on Learning Representations Iclr 2020 · January 1, 2020 We study the following three fundamental problems about ridge regression: (1) what is the structure of the estimator? (2) how to correctly use cross-validation to choose the regularization parameter? and (3) how to accelerate computation without losing too ... Cite

Optimal iterative sketching with the subsampled randomized hadamard transform

Conference Advances in Neural Information Processing Systems · January 1, 2020 Random projections or sketching are widely used in many algorithmic and learning contexts. Here we study the performance of iterative Hessian sketch for least-squares problems. By leveraging and extending recent results from random matrix theory on the lim ... Cite

Asymptotics for sketching in least squares

Conference Advances in Neural Information Processing Systems · January 1, 2019 We consider a least squares regression problem where the data has been generated from a linear model, and we are interested to learn the unknown regression parameters. We consider "sketch-and-solve" methods that randomly project the data first, and do regr ... Cite