Andrzej Galecki, M.D., Ph.D., research professor in the Division of Geriatric and Palliative Medicine, Department of Internal Medicine, and Institute of Gerontology, and research scientist in the Department of Biostatistics at U-M School of Public Health, recently co-authored a new book, "Linear Mixed-Effects Models Using R: A Step-by-Step Approach."
The goal of the book is to describe the most important concepts and features of linear mixed models (LMMs) and to help readers in implementing LMMs using R software. LMMs are an important and powerful class of statistical models that can be used to analyze complex, correlated data. Over the past decade, research has led to a better understanding of LMMs, and an increase in their popularity with applied researchers in a variety of fields, including biostatistics, public health, psychometrics, educational measurement, and sociology. Several statistical software packages contain routines for LMMs, including R. The advantage of R over other systems is that it’s a freely available, dynamically developing, open-source environment for statistical computing and graphics.
The book should allow readers to obtain a basic understanding of LMMs and apply them in practice. To help readers less familiar with this class of linear models, the material in the book builds up incrementally, starting with a summary of the concepts underlying simpler classes of linear models, and carrying them forward to LMMs. All the classes of linear models presented in the book are illustrated using real-life data. The book also introduces several novel R tools for LMMs, including new class of variance-covariance structure for random-effects, methods for influence diagnostics and for power calculations.
Dr. Galecki earned his MSc. in applied mathematics (1977) from the Technical University of Warsaw, Poland, and an M.D. (1981) from the Medical University of Warsaw. He earned a Ph.D. in 1985, and came to U-M in 1990. His co-author is Dr. Tomasz Burzykowski from Hasselt University in Belgium. Financial support came from the Claude Pepper Center from the National Institute of Aging, and from the Belgian Government.