sentences:  All of these categories are offspring of the original concept of option value that was introduced into the cost benefit analysis lexicon in 1964 by Burton Weisbrod to justify individuals' valuation of goods, assets and resources that they do not actually use.In general, it is not possible to use market prices or other revealed preference methods to measure non-use value.As a result, "stated preference" survey methods are generally used, including most prominently contingent valuation methods (CVM).