We analyze the effects of taking an extra private tutorial course on the passing probability and the grade in a course in Macroeconomics at the Business Diploma study program at Copenhagen Business School. The topic is of interest as the students are not supposed to need such an extra course in order to perform well at the exam, but still many students sign up for the courses. We use a combination of administrative data and survey-based student evaluation data. Based on simple models we get the quite surprising result that the participation effect is either negative or insignificant. Due to a potential problem of self selection, as it may be the weaker students who signs up for the courses, we also apply more advanced statistical models. Still, our conclusions are not changed. We argue for the use of gender as an exogenous driver when taking self selection into account.