Many are those to consider that since the development of the curative medicine, the prevention occupied a secondary place in the French health care system. Major concern would have been up to that point to ensure an access to healthcare rather than to support a culture of prevention. Since a few years, various medical dramas (blood transfusion, asbestos, heat wave, growth hormone, flu epidemics,cancers,...) have raised awareness of the concept of “safety” and brings out a new awakening around the prevention problems.The use of prevention allows the individuals and the public authorities to exert a control on the health risks to which they are exposed and to conduct consequent actions in order to improve health and prevent the emergence, the development, the development or the aggravation of the diseases or accidents while promoting individual and collective behaviors that can help to reduce the risk health. One of the answers in front of the health risks is to incite the individuals to more prevention because they are not only consumers of care, but also producers of their health. What is the role of individuals and what is the share of responsibility reserved for each one in the prevention of health risks ? In addition, the prevention of health risks is part of an environment ambiguity and uncertainty because the risks to which are exposed individuals are many different ways and not always well known. It is thus not easy to connect with certainty a risk factor and a health effect for adopting an adequate prevention behavior. In this context of uncertainty, many support the decision models or representations of preferences have been proposed in recent years (and Klibanoff (al. (2005), and Bleichrodt Eeckhoudt (2006), Machina 2009), Etner et al. (2011)).This thesis analyzes the individual behaviors of prevention in front of health risks while focusing on the public policies of prevention proposed. It consists on the one hand in theoretical studies of the behaviors of prevention and management of the health risks by using recent models of preferences. This work analyzes the behavior of the individuals who need to take preventive measures to protect their own health in a context of uncertainty. On the other hand, it is devoted to an empirical study to determine perceptions and information which have the individuals in terms of risk of health. Moreover, throughout this work, we sought to examine the relevance of the theoretical model developed with regard to the policies practiced. The first chapter presents the principles of modeling economic decisions in the presence of a more or less well known health risk. After detailing the different approaches in models of decisions under risk and uncertainty, we have highlighted the importance of the introduction of two-dimensional variables (or multidimensional) in the model of choice to allow to report the multidimensional environment of health risks. The second chapter is an original proposed study on the analysis of preventive health when the individuals have an aversion to ambiguity. In this chapter, we studied individual behavior of prevention in front of an uncertainty on the health status and have showed that aversion to ambiguity encourages the individuals to make more primary and secondary prevention under the assumption of a marginal utility of the increasing wealth with the health status. (...)
