If tax incentives are broadly applicable to all investment, their evaluation is greatly simplified. The advantage of a generalized evaluation model that treats all investment similarly (that is, assumes that tax incentives are available to all classes of assets) is that no distinctions need to be made regarding the physical characteristics of the investment project. However, incentives for pollution-control investment by definition target a selective class of assets. Consequently, they do not directly lend themselves to such a general analysis.