摘要:Background Junior doctors do not feel well prepared when they start into postgraduate training. High self-efficacy however is linked to better clinical performance and may thus improve patient care. What factors affect self-efficacy is currently unknown. We conducted a simulated night shift in an emergency room (ER) with final-year medical students to identify factors contributing to their self-efficacy and thus inform simulation training in the ER. Methods We simulated a night in the ER using best educational practice including multi-source feedback, simulated patients and vicarious learning with 30 participants. Students underwent 7 prototypic cases in groups of 5 in different roles (leader, member and observer). Feeling of preparedness was measured at baseline and 5 days after the event. After every case students recorded their confidence dependent of their role during simulation and evaluated the case. Results Thirty students participated, 18 (60 %) completed all surveys. At baseline students feel unconfident (Mean −0.34). Feeling of preparedness increases significantly at follow up (Mean 0.66, p = 0.001, d = 1.86). Confidence after simulation is independent of the role during simulation (F(2,52) = 0.123, p = 0.884). Observers in a simulation can estimate leader’s confidence independent of their own ( r = 0.188, p = 0.32) while team members cannot ( r = 0.61, p < 0.001). Conclusions Simulation improves self-efficacy. The improvement of self-efficacy is independent of the role taken during simulation. As a consequence, groups can include observers as participants without impairing their increase in self-efficacy, providing a convenient way for educators to increase simulation efficiency. Different roles can furthermore be included into multi-source peer-feedback.