1. A diagnosis method for a rail vehicle, the rail vehicle having at least one measuring device for capturing measured values of at least one measured variable, the method comprising the following method steps: capturing measured values by way of the at least one measuring device of the rail vehicle; transmitting the measured values from a transmitter on the rail vehicle to a receiver of the control center arranged trackside; capturing further measured values by measuring devices that are independent of the rail vehicle; evaluating the measured values from the rail vehicle in a controller of the control center by way of a prescribed algorithm to form an evaluation result; and providing the evaluation result from the controller for output; wherein the evaluation of the measured values from the rail vehicle in the controller of the control center by way of the prescribed algorithm is effected based directly on the further measured values that are captured independently of the rail vehicle by the measuring devices that are independent of the rail vehicle; and wherein the prescribed algorithm includes a trend analysis of the measured values for predicting whether the measured values will exceed a threshold value.