Event history analysis is a set of statistical concepts, models and methods for studying the occurrences of events over time for a number of subjects. The subjects may be humans, animals, or technical equipment, while the events may be deaths, the onset of disease, relapses of cancer patients, or failures of technical equipment. The aim of an investigation may be to establish risk factors for a disease, to study the effect of a medical treatment or to predict future occurrences of an event. Medicine is the main area of application for event history analysis, which is also the main focus of the CAS project. Other important applications include demography, econometrics, sociology and technical reliability.

Although great advances have been made in event history analysis in recent decades, the field still remains dominated by the classical methods for single-event times, and existing methodologies are not always easily adapted to the more ambitious research questions and richer data structures of contemporary research.

The aim of the project has been to make substantial contributions to the methodology for analyzing complex event histories, as indicated by the above-mentioned and related problems.

The CAS year has been an important epoch in a research process that started prior to the project at CAS and will continue after the project year. The group leaders (Aalen, Borgan) and others (Gjessing, Hjort, Samuelsen) have made important contributions to international development in the field. In 2000, Aalen and Borgan took the initiative to establish a working group in event history analysis in the Oslo area. The aim of the working group (called NOREVENT) was to create a common environment for researchers in event history analysis across institutional boundaries for the purpose of (i) strengthening collaboration among statisticians in academia and collaboration between statisticians in academia and biostatisticians at the Norwegian Cancer Registry and the Norwegian Institute of Public Health, (ii) further strengthening international collaboration, (iii) improving the recruitment of young researchers to the field, and (iv) increasing the awareness and knowledge among medical researchers of upto- date methodology for analysing event history data. NOREVENT was soon designated a thematic research area at the Faculty of Medicine, University of Oslo, and its status that was renewed in 2005. At about the same time, NOREVENT changed its name to Centre for Biostatistical Modelling in the Medical Sciences (BMMS).

The project year at CAS made it possible for key BMMS researchers to focus on a number of methodological problems related to the analysis of complex event history data and to benefit from the close contact and collaboration with colleagues from abroad. Having all researchers working away from their home departments, at first-rate facilities and with the support of the professional and friendly staff at CAS provided the best possible conditions for research progress in the form of joint projects and professional discussions.

An application to the Research Council of Norway that will turn BMMS into a Centre of Excellence is through to the second round, and the decision will made in January 2007. If the application goes through, it will create a leading international centre for research in event history analysis and related fields in the Oslo area. Otherwise, BMMS will continue as a thematic research area at the Faculty of Medicine, University of Oslo. In other words, the research from the project year at CAS will be followed up within the framework of BMMS in any case. To this end, the close personal and professional contacts among key international researchers established during the project year will be invaluable, and arrangements have already been made for further research visits to Oslo.