@article{chi_hu_saibaba_rao_2019, title={Going Off the Grid: Iterative Model Selection for Biclustered Matrix Completion}, volume={28}, ISSN={["1537-2715"]}, url={https://doi.org/10.1080/10618600.2018.1482763}, DOI={10.1080/10618600.2018.1482763}, abstractNote={ABSTRACT We consider the problem of performing matrix completion with side information on row-by-row and column-by-column similarities. We build upon recent proposals for matrix estimation with smoothness constraints with respect to row and column graphs. We present a novel iterative procedure for directly minimizing an information criterion to select an appropriate amount of row and column smoothing, namely, to perform model selection. We also discuss how to exploit the special structure of the problem to scale up the estimation and model selection procedure via the Hutchinson estimator, combined with a stochastic Quasi-Newton approach. Supplementary material for this article is available online.}, number={1}, journal={JOURNAL OF COMPUTATIONAL AND GRAPHICAL STATISTICS}, publisher={Informa UK Limited}, author={Chi, Eric C. and Hu, Liuyi and Saibaba, Arvind K. and Rao, Arvind U. K.}, year={2019}, month={Jan}, pages={36–47} }
 @article{hu_lu_zhou_zhou_2019, title={MM ALGORITHMS FOR VARIANCE COMPONENT ESTIMATION AND SELECTION IN LOGISTIC LINEAR MIXED MODEL}, volume={29}, ISSN={["1996-8507"]}, DOI={10.5705/ss.202017.0220}, abstractNote={Logistic linear mixed models are widely used in experimental designs and genetic analyses of binary traits. Motivated by modern applications, we consider the case of many groups of random effects, where each group corresponds to a variance component. When the number of variance components is large, fitting a logistic linear mixed model is challenging. Thus, we develop two efficient and stable minorization-maximization (MM) algorithms for estimating variance components based on a Laplace approximation of the logistic model. One of these leads to a simple iterative soft-thresholding algorithm for variance component selection using the maximum penalized approximated likelihood. We demonstrate the variance component estimation and selection performance of our algorithms by means of simulation studies and an analysis of real data.}, number={3}, journal={STATISTICA SINICA}, author={Hu, Liuyi and Lu, Wenbin and Zhou, Jin and Zhou, Hua}, year={2019}, month={Jul}, pages={1585–1605} }
 @article{zhou_hu_zho_lange_2019, title={MM Algorithms for Variance Components Models}, volume={28}, ISSN={["1537-2715"]}, DOI={10.1080/10618600.2018.1529601}, abstractNote={Abstract Variance components estimation and mixed model analysis are central themes in statistics with applications in numerous scientific disciplines. Despite the best efforts of generations of statisticians and numerical analysts, maximum likelihood estimation (MLE) and restricted MLE of variance component models remain numerically challenging. Building on the minorization–maximization (MM) principle, this article presents a novel iterative algorithm for variance components estimation. Our MM algorithm is trivial to implement and competitive on large data problems. The algorithm readily extends to more complicated problems such as linear mixed models, multivariate response models possibly with missing data, maximum a posteriori estimation, and penalized estimation. We establish the global convergence of the MM algorithm to a Karush–Kuhn–Tucker point and demonstrate, both numerically and theoretically, that it converges faster than the classical EM algorithm when the number of variance components is greater than two and all covariance matrices are positive definite. Supplementary materials for this article are available online.}, number={2}, journal={JOURNAL OF COMPUTATIONAL AND GRAPHICAL STATISTICS}, author={Zhou, Hua and Hu, Liuyi and Zho, Jin and Lange, Kenneth}, year={2019}, month={Apr}, pages={350–361} }
 @article{nolte_anderson_strauss_wang_hu_xu_steen_2016, title={Heal rate of metatarsal fractures: A propensity-matching study of patients treated with low-intensity pulsed ultrasound (LIPUS) vs. surgical and other treatments}, volume={47}, ISSN={["1879-0267"]}, DOI={10.1016/j.injury.2016.09.023}, abstractNote={Whether to treat metatarsal fractures conservatively or surgically is controversial. We test a hypothesis that metatarsal fractures treated conservatively with non-invasive low-intensity pulsed ultrasound (LIPUS) obtain heal rates comparable to current surgical techniques.This is a retrospective observational cohort study, using patient outcomes from a prospectively-collected LIPUS registry required by the U.S. Food & Drug Administration. Registry data were collected over a 5-year period and were reviewed and validated by a registered nurse. Data required for analysis were days-to-treatment (DTT) with LIPUS and a dichotomous outcome of healed versus failed, as assessed by clinical and radiographic criteria. Registry patients (DTT<365days) were propensity-matched to metatarsal fracture patients from a health claims database that includes medical and drug expenses for ∼90.1 million patients. The propensity match was based on patient demographic data (age, gender, body weight, fracture severity, and smoking status).A total of 594 metatarsal fractures were treated with LIPUS, including 161 Jones fractures. Compared to patients in the claims database, LIPUS-treated patients were more likely to: be overweight or obese; be male; have open fracture; and smoke (all, P<0.0001), suggesting that these variables were perceived as nonunion risk factors by prescribing physicians. After propensity-matching, none of these differences between the registry and the health claims database remained significant. The heal rate with LIPUS treatment was 97.3%, comparable to the heal rate of 95.3% among claims patients in 2011 who did not receive LIPUS (P=0.0654). When fresh fractures (0-90days) and delayed unions (91-365days) were analyzed separately, the LIPUS fresh fracture heal rate was superior to claims patients (P=0.0381), and the delayed union heal rate was comparable. After exclusion of registry patients who received surgery, heal rate with LIPUS alone (97.4%) was significantly better (P<0.0097) than the heal rate for matched patients in 2011 (94.2%).LIPUS significantly improved the heal rate of metatarsal fractures <1year old without surgery (P=0.0097). Metatarsal fractures treated with LIPUS alone have a heal rate comparable to fractures treated by surgical intervention.}, number={11}, journal={INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED}, author={Nolte, Peter and Anderson, Robert and Strauss, Elton and Wang, Zhe and Hu, Liuyi and Xu, Zekun and Steen, R. Grant}, year={2016}, month={Nov}, pages={2584–2590} }