Research
My research expertise is in data integration from multiple sources for cardiovascular health study with an emphasis on health disparities in underserved populations defined by race/ethnicity, sexual orientation, and socioeconomic factors. Many issues and challenges could arise when integrating data from multiple sources. Different sources usually generate data in different forms: some studies release individual data, while others only release aggregate/summary data. Study designs, data types, model assumptions, and analysis results often vary across different studies, even for the same scientific problem. The measurements for the set of variables may also differ considerably from study to study. I am leading an effort to address these problems, in order to draw more accurate conclusions and make more insightful decisions in the cardiovascular study.
Biography
Dr. Liu is a Staff in biostatistics and data science in the department of quantitative health sciences at the Cleveland Clinic Foundation (CCF) Lerner Research Institute (LRI), and a Professor in Medicine in the Case Western Reserve University School of Medicine. He leads a LRI biostatistics core team to provide scientific method guidance and consulting services for LRI principal investigators in basic and translational sciences to facilitate their grant preparation and submission. The guidance areas provided includes the optimal experimental design, power analysis, statistics analysis plan, sample size justification, data curation and integration, design-related statistical techniques and approaches, and result interpretations.
Dr. Liu has a long-history record of publications in statistical methods as applied to public health and clinical and biological sciences. The methods he has developed and used in his research programs (either independent or collaborative) include, but are not limited to, repeated measures/longitudinal models, latent class/trait models, mixed effects models, missing data models, hierarchical/multilevel models, GWAS, high-dimensional high throughout methods, and data reduction methods (PCA, FA, SEM). He has led or co-led multiple NIH-funded projects and carried out methodology development research on the longitudinal study of substance use, mental disorders, cardiovascular risk, and hypertension control. The main goal of his research program is to develop innovative analytical approaches and data science technology to improve the precision and accuracy of scientific findings in health sciences.
Before joining CCF, Dr. Liu held professorship in the University of Michigan Ann Arbor, where he conducted research in innovative statistical methods and provided support for other PI’s grants, taught analytical courses for medical, nursing and public health programs, and mentored graduate students for dissertations and research publications.
Dr. Liu has published over 150 papers in statistical and health science journals and presented numerous invited talks in the national and international conferences. After work, he enjoys doing physical activities (jogging, hiking, basketball) and listening to music.
Education & Professional Highlights
Appointed
2021
Education
MS in Statistics, University of Florida, Gainesville, FL, 2002
PhD in Statistics, University of Florida, Gainesville, FL, 2006
Professional Society Affiliation
American Statistical Association
American Public Health Association
International Chinese Statistical Association
Institute of Mathematical Statistics
Research
There are three main lines of inquiry in my research. The first line focuses on statistical methodology that includes the development and application of innovative statistical methods to address emerging issues in health fields. I am interested in investigating the problems faced when integrating data from multiple sources. My expertise in methodology includes Bayesian statistics, repeated measure models, missing data models, high dimensional statistics, and latent variable models. The second line of my research involves cardiovascular health studies with a focus on hypertension and related risk factors (clinical, behavioral, diet, or environmental factors) that may cause health disparities in uncontrolled hypertension and other cardiovascular diseases. I have led or co-led multiple cardiovascular projects that are breakdown assignments of NIH- or HRSA-funded centers/programs covering racial disparity, drug therapy, and tele-home care. The third line of my research involves consulting and collaborating with investigators and research scientists in other fields, including substance use, mental disorder, health disparities, obesity, genetic epidemiology, cancer, etc., to improve scientific findings in the related areas. All these research interests align well with my main role of leading LRI biostatistics support team and providing scientific method support and guidance for LRI investigators in grant preparation, manuscript writing, and data report.
Our Team
Selected Publications
Feigin VL, Vos T,··· Liu XF, Lo WD, ···Adelson JD, Murray CJL. Burden of Neurological Disorders Across the US From 1990-2017 A Global Burden of Disease Study. JAMA Neurology 2021; 78:165-176.
Lozano R, Fullman N,··· Liu XF et al. GBD 2019 Universal Health Coverage Collaborators. Measuring universal health coverage using the UHC effective coverage index in 204 countries and territories, 1990–2019: a systematic analysis from the Global Burden of Disease Study 2019. The Lancet 2020; 396: 1250-1284.
Liu XF, Baylin A, Levy PD. Vitamin D deficiency and insufficiency among US adults: prevalence, predictors, and clinical implications. British Journal of Nutrition 2018; 119:928-936.
Liu XF, Byrd JB, Rodriguez CJ. Use of physician-recommended non-pharmacological strategies for hypertension control among hypertensive patients. Journal of Clinical Hypertension 2018; 20:518-527.
Liu XF, Zhu TH, Manojlovich M, Cohen HW, Tsilimingras D. Racial/ethnic disparity in the associations of smoking status with uncontrolled hypertension subtypes among hypertensive subjects. Plos One 2017; 12(8): e0182807
Liu XF, Wang K. Generalized latent trait models for multiple correlated health endpoints. Proceedings of American Statistical Association 2016; pp. 1121-1129.
Liu XF, Rodriguez CJ, Wang KS. Prevalence and trends of isolated systolic hypertension among untreated adults in the United States. Journal of the American Society of Hypertension 2015; 9(3):197-205.
Liu XF, Tsilimingras D, Paul TR. Prevalence and changes of isolated systolic hypertension among US Non-Hispanic black adults in 1999-2010. Hypertension Research 2014; 37(7):685-691.
Liu XF, Song P. Is the association of diabetes with uncontrolled blood pressure stronger in Mexican Americans and blacks than in whites among diagnosed hypertensive patients? American Journal of Hypertension 2013; 26 (11):1328-1334.
Zheng S, Gupta AK, Liu XF. A matrix variate generalization of the skew pearson type VII and skew T distribution. Mathematical Sciences Research Journal 2012; 16(6):136-156.
Wang KS, Liu XF, Zhang QY, Aragam N, Pan Y. Parent-of-origin effects of FAS and PDLIM1 in attention-deficit hyperactivity disorder. Journal of Psychiatry and Neuroscience 2012; 37(1):46-52.
Liu XF, Liu M, Tsilimingras D, Schiffrin EL. Racial disparities in cardiovascular risk factors among diagnosed hypertensive subjects. Journal of the American Society of Hypertension 2011; 5(4):239-248.
Liu XF, Wang KS, Lee K. The Association of standardized estimated glomerular filtration rate with the prevalence of hypertension in adults in the United States. Journal of Human Hypertension 2011; 25(8):469-475.
Baker MK, Hillhouse JJ, Liu XF. The Effect of initial indoor tanning with mother on current tanning patterns. Archives of Dermatology 2010; 146(12):1427-1428.
Liu XF, Daniels MJ, Marcus B. Joint models for the association of longitudinal binary and continuous processes with application to a smoking cessation trial. Journal of the American Statistical Association 2009; 104:429-438.
Liu XF, Roth J. Development and validation of an infant morbidity index using latent variable models. Statistics in Medicine 2008; 27(7):971-989.
Liu XF, Daniels MJ. A new efficient algorithm for sampling a correlation matrix based on parameter expansion and re-parameterization. Journal of Computational and Graphical Statistics 2006; 15(4):897-914.