I am currently the principal investigator of the NIH funded project
"Longitudinal Analysis for Diverse Populations" (R01CA096885). My work on this
project involves the quasi-least squares (QLS) approach for analysis of longitudinal
data. For more description of our project and of my colleagues and the students who are
working with me on this research, please click on the appropriate link in the link
section of this web-site. 

In addition to my work on the LADP project, I am the lead statistician on several
collaborative studies in Psychiatry and Pediatrics. I am also a co-investigator on NIH
funded interventions to promote weight loss in African-American women. A feature of these
collaborative studies is that they are all longitudinal and yield data suitable for
analysis with the methods developed, or studied, in our LADP project. 

To complement my research activities, I am actively involved in teaching in our
department. For example, I am currently teaching Linear Models in our Phd program in
Biostatistics. I am also working with several students on research projects. For more
description of student involvement on the LADP project, please see the link for our
project.

General Biostatistics

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Improved generalized estimating equation analysis via xtqls for implementation of quasi-least squares in Stata (with Sarah J. Ratcliffe and Mary Leonard), UPenn Biostatistics Working Papers (2006)
 

Longitudinal Data Analysis and Time Series

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On The Violation Of Bounds For The Correlation In Generalized Estimating Equation Analyses Of Binary Data From Longitudinal Trials (with Wenguang Sun, Xin Tu, and Jay Amsterdam), UPenn Biostatistics Working Papers (2006)
 

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Use of Unbiased Estimating Equations to Estimate Correlation in Generalized Estimating Equation Analysis of Longitudinal Trials (with Wenguang Sun and Mary Leonard), UPenn Biostatistics Working Papers (2006)