Efficiency factor is a ratio of some measure of performance to an expected value.
In data communications, the factor is the ratio of the time to transmit a text automatically at a specified modulation rate to the time actually required to receive the same text at a specified maximum error rate.
[1] All of the communication facilities are assumed to be in the normal condition of adjustment and operation.
Telegraph communications may have different temporal efficiency factors for the two directions of transmission.
Efficiency factors are used in performance rating and remuneration calculation exercises.