This paper presents and discusses empirical results from a survey about the research practice of Danish chemistry students, with a main focus on the question of anomalous data. It seeks to investigate how such data is handled by students, with special attention to so-called 'questionable research practices' (QRPs) where anomalous data are simply deleted or discarded. This question of QRPs is of particular importance as the educational practices students experience may influence how they act in their future professional careers, for instance in research. The ethical evaluation of QRPs however is not univocal. In parts of the literature QRPs are seen as unquestionably bad, while in other parts of the literature certain QRPs are seen as a necessary aspect of scientific practice. Results from the survey of Danish chemistry students shows that many students engage in certain types of questionable practices, and that a large minority of the students have been actively encouraged by their teachers to engage in such practices. The paper discusses to what extent and under what circumstances such instructional practices can be defended and suggests how the instructional practice connected to the handling of anomalous data can be improved.
Keywords: Academic dishonesty; Laboratory practice; Professional ethics; Questionable research practices.