 The study investigates potential determinants of dropout in web-based prospective studies on psychedelic use, using logistic regression models to examine demographic, psychological trait and state, and psychedelic-specific predictors of attrition. The results show that age, educational levels, conscientiousness and extroversion were significant predictors of dropout, while baseline attitudes toward psychedelics and the intensity of acute challenging experiences were not. These findings suggest transdisciplinary relevance and contextualize concerns about problematic biases in related data. This article was authored by Sebastian Hubner, Aline Hagen, Mendel Kalen, and others.