“…This approach dates back to C.M. Walsh [1901, 19211 andIrving Fisher 11911, 1921, 19221, but in more recent times the main contributors have been Eichhorn [1976, 19781 and his co-workers; see Eichhorn and Voeller [1976] and Funke and Voeller [1978, 19791. In Section 2, we list some 20 tests or mathematical properties that have been suggested as desirable for an output quantity index Q(p', p', y", y'), and in Section 3, we show that the Fisher ideal quantity index QF defined by equation (4) is the unique function which satisfies all of these tests. Thus, our first approach to the measurement of productivity change in the multiple input and output case leads to the Fisher index of productivity change PrF defined by…”