The researcher must often establish the link between a theoretical world (a world of the concepts), and the empirical world (a world of data). Establishing a connection between concepts and data constitutes one of the most important and most difficult steps of the research process. This article explains how this consists of a translation procedure that incorporates two processes; measurement and abstraction. Measurement consists of selecting the instruments or indicators needed to translate a concept into data. Abstraction involves the translation, through coding and classification, of data into concepts. This methodological article focuses on the central questions relating to the design of one’s own process of translation by using theoretical references and relevant examples.