[Relevance of design and structure of data-bases in research].

Research studies require a methodological frame providing concepts and approach procedures. The so-called scientific method encompasses systematic data collection and problem solving notions. Epidemiology and statistics are essential disciplines in this process. The goal of this course is to provide knowledge for design of databases, with special attention to the definition of variables and to measurement scales. A small database on headache is made using fictitious information. A questionnaire designed for this purpose is used as a foundation. Finally, we present a graphic design on the percentage distribution of the variable gender, as an example of the summary statistics.