Stated Preference (SP) methods are survey-based approaches to non-market valuation. A sample of the reference population is asked to complete a questionnaire where a good or service is offered in a hypothetical market, for example, the improvements in water quality or biodiversity associated with an intervention policy. Willingness to pay (WTP) for the good is then estimated using statistical procedures. 

The main advantage of SP methods over Revealed Preference (RP) methods is that they allow the estimation of non-use and option values. Their main disadvantage is hypothetical bias since respondents state their preferences in a hypothetical market (Boyle, 2017). For example, respondents may provide an inaccurate WTP of hypothetical goods/services due to a lack of understanding or familiarity.

SP methods are categorized into Contingent Valuation (CV) and Discrete Choice Experiments (DCE). In CV surveys, people are asked to state their willingness to pay (WTP) or willingness to accept (WTA) for a hypothetical change in the provision of a good (Mitchell & Carson, 1989). In DCE surveys, respondents are asked to make choices over goods or policies, defined in terms of attributes and levels in hypothetical alternative scenarios. That is, CV considers the good (e.g., the non-market value of a beach) as a whole and DCE as a “bundle of attributes” (Riera et al., 2012).