Time use study is an innovation of the conventional stated preference techniques, in particular taken from the contingent valuation approach. In this case, the payment vehicle is expressed in labour hours rather than monetary units (use in the classical willingness to pay studies). Willingness to give up time (WTT) creates a hypothetical scenario using surveys to estimate the value of ecosystem services by directly asking people how much time they would willing to invest for a change in the quantity or quality of a given ecosystem service or conservation plan. This approach is also useful in areas with income constrains where money is basically used for essential goods.