 |
|
DISCUSSIONThe four techniques of this chapter all use data from surrogate markets. They use different kinds of data from different kinds of surrogate and use it in different ways. Hence they differ in their theoretical and market validity. Theoretical validity The travel-cost, property-value and wage-differential techniques all apply the notions of willingness to pay/accept and opportunity cost. Over the years, users of these techniques have refined the procedures and interpretations. For this reason, these techniques require careful and skilled management but are theoretically valid. In contrast, the theoretical validity of the proxy-good technique is more open to question. The technique relies on finding a close proxy for the effect in question and the results achieved are only as reliable as the goods are close substitutes. Market validity All four techniques use actual prices and costs from actual exchanges in market places. Apart from the proxy-good technique, the surrogate is directly and causally related to the environmental effect of interest. The travel-cost, property-value and wage-differential techniques are all supported by market tests. |
 |
©İsmail Güneş |