Comment: The Unique, Real Internal Rate of Return

Abstract

In the June 1978 issue of this Journal, Herbst [2, p. 363] cautioned the reader to beware of a unique, real internal rate of return (IRR) because such a return is “an incorrect measure of the return on investment” for a mixed project. While it is true, as discussed by Teichroew, Robichek and Montalbano (TRM) [4], and now by Herbst, that a mixed project may have a unique IRR, several additional observations developed by TRM should be added to Herbst's discussion. These comments will clarify the implications of Herbst's paper for a decision maker who has a mixed project with a unique real IRR.