Comments on Longmore's Article

In his recent paper [3], Dean R. Longmore develops a new concept of the Payback Period project evaluation criterion, the so-called Time-Adjusted Payback Period, which is supposed to be NPV-compatible and is, therefore, expected by the author to address the needs of practitioners. In this paper, it is indicated that the formulation of the proposed criterion is mathematically incomplete, and its complete version is presented. It is also shown, using numerical examples, that the criterion devised in [3] does not reflect the true content of its name and constitutes, instead, an artificial profitability index. Although this index, in its complete version, is indeed NPV-compatible, it does not, however, offer any advantages over the NPV.