[Hierarchies according to the level of evidence of source data, before their integration in the synthesis, in the matter of therapeutic efficacy].
The discipline therapeutic information uses the concept of the level of evidence for source data concerning therapeutic efficacy, and its ordering before integration in syntheses. In this paper we will start by considering the problems raised by the definition of the level of evidence in terms of the dimensions it covers. We have differentiated three components: clinical pertinance of the question asked, the methods used to reply and the quality of the data collected. Second, we will examine the different criteria important for each of these three dimensions. There are many criteria possible which do not all have the same weight, and thus for any non-arbitrary tool developed to enable the level of evidence to be ordered, it is necessary to know the weight of the different criteria. Thirdly, we will present the techniques used for working with multicriteria situations in econometrics which represent a methodology we propose using to apply in our context. To do so we need to build a 'reference' base for the level of evidence using 'experts' opinions which will help us to examine the weights of the different criteria. This approach, in conjunction with some epistemological and sociological considerations, may contribute to a better understanding of the different dimensions of this concept.