The present authors find it impossible to compare their work with that of Powell & Tucker (Scand Audiol 5, 167, 1976) due to the lack of original data in the latter paper. The present authors papers were not written with the prime view of presenting predictive values but of reporting data on hearing aid users. The predictive value of our results has been largely and not very carefully inferred by Powell & Tucker. The predictive values of gain or output may be inferred from current research and the Powell & Tucker paper confirms the previous work rather than repudiates it. It is obvious that research workers should co-operate in using clearly stated methods and publishing original data in their papers. Furthermore it is important that the terminology used is of a standard form--or if not, that each new term is clearly defined.