An error frequently committed when making cash flow projections involves escalating revenue items at one rate and cost items at another rate, without any real justification for doing so. When these escalation rates differ, it is important to furnish an explanation along with the projections. Escalating revenues at a higher rate than costs will introduce a basis in favor of proceeding with the project. An economically unprofitable project may then appear to be profitable.
Some financial economists recommend preparing the projections for a project on the basis of dollars of constant purchasing power (or, more simply, constant dollars). Constant dollars differ from so-called current dollars, which is the unit of measurement employed for the Cogeneration Project, in that constant dollars have the effect of general inflation removed. Many companies have found it useful to prepare cash flow projections in constant dollars when evaluating a project that would be developed in a high-inflation economy and would have certain critical revenue or cost items received or paid, respectively, in the local currency.
When a project's revenues and costs are all denominated in a single freely tradable currency, and the inflation rate in the country that issued the currency is comparatively low (no more than a single-digit rate), the extra work required to prepare the projections on a constant-dollar basis is seldom justified. A better analytical approach is to specify the inflation assumptions, as in Table 8.2, and then show the effects of different inflation assumptions in a separate sensitivity analysis.