Summer 2008 Workshop

Held on June 5, 2008 at the Wyndham Glenview Suites.

The 24th Annual Summer Workshop of the Northeastern Illinois Chapter of the American Statistical Association was given on the topic of:

Applied Longitudinal Analysis
Garrett Fitzmaurice, ScD, ASA Fellow


The goal of the workshop was to provide an introduction to statistical methods for analyzing longitudinal data. The main emphasis was the practical rather than the theoretical aspects of longitudinal analysis. The workshop begins with a review of established methods for analyzing longitudinal data when the response of interest is continuous. A general introduction to linear mixed effects models for continuous responses is presented. When the response of interest is categorical (e.g., binary or count data), a number of extensions of generalized linear models to longitudinal data have been proposed. We present a broad overview of two main types of models: "marginal models" and "generalized linear mixed models". While both classes of models account for the within-subject correlation among the repeated measures, they differ in approach.  Moreover, these two classes of models have regression coefficients with quite distinct interpretations and address somewhat different questions regarding longitudinal change in the response. In this workshop we highlight the main distinctions between these two types of models and discuss the types of scientific questions addressed by each. The presentation follows Chapters 1-2, 8, 10-13 of the textbook: Fitzmaurice, G.M., Laird, N.M. and Ware, J.H. (2004). Applied Longitudinal Analysis (Wiley Series in Probability and Statistics). The textbook is not required for the workshop  

Biographical Background

Garrett Fitzmaurice is Associate Professor of Biostatistics at the Harvard School of Public Health, Associate Professor of Psychiatry (Biostatistics) at the Harvard Medical School and Foreign Adjunct Professor of Biostatistics at the Karolinska Institute, Sweden. He is a Fellow of the American Statistical Association and a member of the International Statistical Institute. He has served as Associate Editor for the Journal of the Royal Statistical Society (Series B), Biostatistics, and Biometrics; currently, he is Statistics Editor for the journal Nutrition, Editor of the Wiley Series in Probability and Statistics, and Editor of the Chapman & Hall/CRC Series of Handbooks of Modern Statistical Methods. His research and teaching interests are in methods for analyzing longitudinal and repeated measures data. A major focus of his methodological research has been on the development of statistical methods for analyzing repeated binary data and for handling the problem of attrition in longitudinal studies. Much of his collaborative research has concentrated on applications to mental health research, broadly defined. He is the co-author of a recently published textbook on “Applied Longitudinal Analysis” (Wiley, 2004) and co-editor of a new book “Longitudinal Data Analysis”, to be published by Chapman & Hall/CRC in Spring 2008. He has taught several courses and workshops on this topic in universities as well as industry, both in the US and abroad. He received the 2006 award for Excellence in Continuing Education from the American Statistical Association for this tutorial presentation at the Joint Statistical Meetings.