This presentation was prepared for the course 'Methodology for Urbanism' at the faculty of Architecture of the Delft University of Technology. It builds on the ideas of Biggs and Buchler (2008) about Practice based research (PbR) and tries to understand and explain "research by design" at TU Delft. We consider that there are several problems with "research by design". The main problem is the lack of common definition. Each researcher/designer seems to use the expression in a different way. This makes it impossible to convey ideas about research by design to an external audience. Students also face problems, because they are generally unable to explain the actions or steps connected to research by design. The beginning of the process is particularly difficult: does research by design tackle an assignment coming from somewhere else? Is there an initial question to be answered? What does you want to "know" when you do research by design?