How is the Failure-to-Enrol Rate (FER/FTE) defined in detail?
Due to the statistical nature of the failure-to-enrol rate, a large number of enrolment attempts have to be undertaken to get statistical reliable results. The enrolment can be successful or unsuccessful. The probability for lack of success (FER(n)) for a certain person is measured: FER(n) = Number of unsuccessful enrolment attempts for a person (or feature) n Number of all enrolment attempts for a person (or feature) n These values are better with more independent attempts per person/feature. The overall FER for N participants is defined as the average of FER(n): FER = 1 N N n=1 FER(n) The values are more accurate with higher numbers of participants (N). Alternatively, the median value may be calculated. Finally, the result of an enrolment attempt has to be defined exactly: An enrolment attempt is successful if the user interface of the application provides a “successful”- or “finished” message. An enrolment attempt is unsuccessful if the user interface of the application provides an
