|2016 - Present||Affiliate Associate Professor, University of Washington ‐ Department of Biostatistics|
|2015 - Present||Associate Member, Fred Hutchinson Cancer Research Center ‐ Program of Biostatistics and Biomathematics|
|2010 - 2016||Affiliate Assistant Professor, University of Washington ‐ Department of Biostatistics|
|2009 - 2015||Assistant Member, Fred Hutchinson Cancer Research Center ‐ Program of Biostatistics and Biomathematics|
functional data analysis, longitudinal data analysis, measurement error and hypothesis testing under nonstandard conditions, latent variable models
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave N, M2-B500
Seattle, WA 98109
Statistical Methodology (15)
Testing homogeneity in semiparametric mixture case-control models Communications in Statistics: Theory and Methods (2016)
Recently, Qin and Liang (Biometrics, 2011) considered a semiparametric mixture case-control model and proposed a score test for homogeneity. The mixture model is semiparametric in the sense that the density ratio of two distributions is ...
A unified powerful set-based test for sequencing data analysis of GxE interactions Biostatistics (2016)
The development of next-generation sequencing technologies has allowed researchers to study comprehensivelythe contribution of genetic variation particularly rare variants to complex diseases. To date many sequencing analyses of rare variants have focused on marginal genetic ...
Hypothesis testing for functional linear models Biometrics (2016)
Functional data arise frequently in many biomedical studies, where it is often of interest to investigate the dynamic association between functional predictors and a scalar response variable. While functional linear models (FLM) are widely used ...
Model-robust Inference for Continuous Threshold Regression Models Biometrics (2016)
We study threshold regression models that allow the relationship between the outcome and a covariate of interest to change across a threshold value in the covariate. In particular we focus on continuous threshold models, which ...
Change Point Testing in Logistic Regression Models with Interaction Term Statistics in Medicine (to appear) (2014)
The threshold effect takes place in situations where the relationship between an outcome variable and a predictor variable changes as the predictor value crosses a certain threshold/change point. Threshold effects are often plausible in a ...
Hypothesis Testing for an Extended Cox Model with Time-Varying Coefficients Biometrics (2014)
In many randomized clinical trials, the log-rank test has routinely been used to detect a treatment effect under the Cox proportional hazards model for censored time-to-event outcomes. However, it may lose power substantially when the ...
On Likelihood Ratio Tests When Nuisance Parameters are Present Only Under the Alternative Statistical Science (2014)
In parametric models, when one or more parameters disappear under the null hypothesis, the likelihood ratio test statistic does not converge to chi-square distributions. Rather, its limiting distribution is shown to be equivalent to that ...
Testing gene-environment interactions in the presence of measurement error UW Biostatistics Working Paper Series (Working Paper 405) (2014)
In genetic and genomic studies, it is important to study gene-environment interactions (GxE) in order to understand the etiology of complex diseases. Compared to marginal analysis, one difficulty with GxE arises from the fact that ...
Proportional mean residual life model for right-censored length-biased data Biometrika (2012)
To study disease association with risk factors in epidemiologic studies, cross-sectional sampling is often more focused and less costly for recruiting study subjects who have already experienced initiating events. For time-to-event outcome, however, such a ...
Likelihood Ratio Testing for Admixture Models with Application to Genetic Linkage Analysis Biometrics (2011)
We consider likelihood ratio tests (LRT) and their modifications for homogeneity in admixture models. The admixture model is a special case of two component mixture model, where one component is indexed by an unknown parameter ...
Multilevel latent class models with Dirichlet mixing distribution Biometrics (2011)
Latent class analysis (LCA) and latent class regression (LCR) are widely used for modeling multivariate categorical outcomes in social sciences and biomedical studies. Standard analyses assume data of different respondents to be mutually independent, excluding ...
Generalized Multilevel Functional Regression Journal of the American Statistical Association (2009)
We introduce Generalized Multilevel Functional Linear Models (GMFLMs), a novel statistical framework for regression models where exposure has a multilevel functional structure. We show that GMFLMs are, in fact, generalized multilevel mixed models. Thus, GMFLMs ...
Multilevel Functional Principal Component Analysis Annals of Applied Statistics (2009)
The Sleep Heart Health Study (SHHS) is a comprehensive landmark study of sleep and its impacts on health outcomes. A primary metric of the SHHS is the in-home polysomnogram, which includes two electroencephalographic (EEG) channels ...
Nonparametric Signal Extraction and Measurement Error in the Analysis of Electroencephalographic Activity During Sleep Journal of the American Statistical Association (2009)
We introduce methods for signal and associated variability estimation based on hierarchical nonparametric smoothing with application to the Sleep Heart Health Study (SHHS). SHHS is the largest electroencephalographic (EEG) collection of sleep-related data, which contains, ...
Physical Activity and Accelerometry (7)
An activity index for raw accelerometry data and its comparison with other activity metrics PLOS ONE (2016)
Accelerometers have been widely deployed in public health studies in recent years. While they collect high-resolution acceleration signals (e.g., 10-100 Hz), research has mainly focused on summarized metrics provided by accelerometers manufactures, such as the ...
Classifiers for Accelerometer-Measured Behaviors in Older Women Medicine & Science in Sports & Exercise (2016)
Machine learning methods could better improve detection of specific types of physical activities and sedentary behaviors from accelerometer data. No studies in older populations have developed and tested algorithms for walking and sedentary time in ...
Calibrating physical activity intensity for hip-worn accelerometry in women age 60 to 91 years: The Women’s Health Initiative OPACH Calibration Study Preventive Medicine Reports (2015)
We conducted a laboratory-based calibration study to determine relevant cutpointsfor a hip-worn accelerometer among women >=60 years, considering both type and filtering ofcounts.
Development and application of an automated algorithm to identify a window of consecutive days of accelerometer wear for large‑scale studies BMC Research Notes (2015)
Some accelerometer studies ask participants to document in a daily log when the device was worn. These logs are used to inform the window of consecutive days to extract from the accelerometer for analysis. Logs ...
Simultaneous Association of Total Energy Consumption and Activity-Related Energy Expenditure With Risks of Cardiovascular Disease, Cancer, and Diabetes Among Postmenopausal Women American Journal of Epidemiology (2014)
Total energy consumption and activity-related energy expenditure (AREE) estimates that have been calibratedusing biomarkers to correct for measurement error were simultaneously associated with the risks of cardiovascular disease, cancer, and diabetes among postmenopausal women who ...
Physical Activity Assessment: Biomarkers and Self-Report of Activity-Related Energy Expenditure in the WHI American Journal of Epidemiology (2013)
We used a biomarker of activity-related energy expenditure (AREE) to assess measurement properties of selfreported physical activity and to determine the usefulness of AREE regression calibration equations in theWomen’s Health Initiative. Biomarker AREE, calculated as ...