The gains are realised when the owner sells the asset and cashes in the gains. Smeeding and Moon (1980) have compared alternative methods for the evaluation of a set of services, finding negligible differences between the cost of production and more subjective metrics such as the utility value. See OECD website, “Going social: the great tax-benefit balancing act” on wages and benefits indicators, wwuj.oecd.org/els/bene/itsandujagesoecdmdicators.htm.