Overdispersion is commonly encountered in modelling data. Statisticians and those working in the application areas need to know how to deal with it, and this book provides a complete source for identifying and handling overdispersion. With increasing focus on modelling in the applied sciences, this book is a welcome addition to the modelling literature for researchers and practitioners working in biometrics, medicine, and epidemiology. It is also excellent supplementary reading for a graduate or graduate-level course in statistical modelling.