Paul D. Allison, Ph.D., is Professor of Sociology at the University of Pennsylvania, and President of Statistical Horizons LLC. You can visit his website at www.StatisticalHorizons.com. After completing doctoral work in sociology at the University of Wisconsin, he did postdoctoral study in statistics at the University of Chicago and the University of Pennsylvania. He has published eight books and more than 60 articles on topics that include linear regression, log-linear analysis, logit analysis, probit analysis, measurement error, inequality measures, missing data, Markov processes, and event history analysis. Much of his earlier research was focused on career patterns of academic scientists. At present, his principal methodological research is focused on the analysis of longitudinal data, especially with determining the causes and consequences of events, and on methods for handling missing data. Each summer he teaches 5-day workshops on survival analysis and logistic regression analysis that draw about 90 doctorate-level researchers from around the U.S. At Penn, he teaches advanced graduate courses on event history analysis, categorical data analysis, and structural equation models with latent variables. A former Guggenheim Fellow, Allison received the 2001 Lazarsfeld Award for distinguished contributions to sociological methodology. In 2010, he was elected as a Fellow of the American Statistical Association.