In our etiologic research, we epidemiologists need to leave behind the concepts of ‘cohort’ study and ‘case–control’ study and adopt that of the etiologic study as the singular substitute for these. With this sentence, the famous epidemiologist Professor Olli S. Miettinen began his personal re ection on the future of the epidemiology [1]. He sought to highlight the fact that the role of the epidemiologist should be mainly focused on aetiological research. Nevertheless, the widespread idea still exists that epidemiology is limited to purely providing gures and descriptive data on the frequency and distribution of disease. Indeed, it is more than likely that the precise aim of those rst classic epidemiological steps, i. e. , methods essentially based on describing the distri- tion of a given disease, is still not all that well understood by many scientists, let alone the general public. Such descriptions seek to generate hypotheses and afford explanations for key factors (be these risk factors or the presumable causes th- selves), which might justify differences in terms of persons, time or place and, in turn, ultimately serve to develop preventive measures and/or gain quality-adjusted life years. To restrict the goals of epidemiology to activities exclusively concerned with reporting gures or even complex statistical results is a great mistake, one that renders it dif cult to take full advantage of the epidemiologist’s true role, which is “to study disease determinants and to assess the actual impact of factors involved in their development, distribution and dissemination”.