A Review of: “An Introduction to Mathematical Finance: Options and Other Topics By Sheldon M. Ross” Cambridge University Press,New York,New York, 1999, xv + 184 pp. ISBN ( 521-77043-2. List: $37.95. (hardback)

Surveys of businesses' capital budgeting practices reveal that the IRR is much preferred over the NPV as an investment decision making tool even though business scholars prescribe the NPV as theoretically optimal. Here practitioners' preference for the IRR is explained through ergonomics: the IRR is treated as a display method. As such it is more compatible with decision makers' expectations and therefore, is more cognitively efficient. Because the IRR is expressed as an interest rate, it more closely resembles an analog display, in which the IRR is simply compared to the required return. In contrast, the NPV is stated in dollars, resembling more a very precise digital display. Academicians should reorient their efforts from promoting the NPV to teaching methods to ameliorate the pitfalls of the IRR.