Although it is true that some investment decisions fall into those categories, most don’t. In most cases, investments are irreversible and, in reality, capable of being delayed. A growing body of research shows that the ability to delay an irreversible investment expenditure can profoundly affect the decision to invest. Ability to delay also undermines the validity of the net present value rule. Thus, for analyzing investment decisions, we need to establish a richer framework, one that enables managers to address the issues of irreversibility, uncertainty, and timing more directly.