Determination of gas turbine degradation

Method in which at a measurement time point a set of measurement values are recorded and, from the set, a state vector is determined that characterizes the degradation of the gas turbine. To detect an incorrect value, and therefore a faulty sensor, an estimate of the measurement value is made and any measurements that deviate significantly from it are not considered in determining the state vector and are regarded as faulty. An Independent claim is also included for a corresponding computer program for implementing the method.