The analysis of statistical data is a critical element in road safety studies. For example, specific projects or programs may be implemented with the analyst asked to answer the question, "What has been the effect of this project (program) on accident frequency and/or severity?" Are there any interdependencies or contribut­ ing effects due to the age, sex or driving experience of involved motorists? What is the contribution, if any, of roadway design, time of day, traffic density, etc.?" To answer, or to provide insight into, these types of questions, contingency tables are often used to display frequency or count data. The subsequent analysis of these contingency tables is the principal form of this book. Because of recent advances in the underlying statistical methodology and procedures, and because of the increasing interest in the application of contingency table analysis to road safety studies, an Advanced Study Institute (ASI) directed to this topic was held at the Sogesta Conference Center, Urbino, Italy, during the period 18-29 June 1979. The ASI was funded by the Scientific North Atlantic Treaty Organization (NATO) as part of its Advanced Study Institutes Programme. The contents of this book, with two exceptions described below, represent the Proceedings of the ASI.