1. A method for deriving a device-specific value from a physical unclonable function realized on a circuit unit, the method comprising: ascertaining a first response from application of a first challenge to the physical unclonable function on the circuit unit at least once; ascertaining at least one second response from application of a second challenge to the physical unclonable function at least once; deriving, by a processor, a respective categorization information item from a respective response, the deriving comprising allocating the respective response to one of at least two respective categories with regard to a statistical variation, the at least two respective categories being stipulated by at least one prescribable threshold value; and deriving, by the processor, the device-specific value from at least two of the respective categorization information items.