The German legislation on medicine demands that each person examining or treating patients must prove the quality of their work. That is done by way of "external evidence", by application of qualified studies or, if in default of those, by documentation on results and evaluation of each individual patient ("internal evidence"). Such evidences pertain to diagnostics (methods and their evaluation), treatment (medication and physical therapy) and the organization of work (staff, timeframes, available space etc.). The demand of assuring quality means that those methods which have no proven efficiency are automatically dropped, which in turn brings cost reduction.