Sample selection bias and theoretical validity tests of the non-use value of an environmental good

This paper addresses the issue of sample selection bias in theoretical validity tests of willingness to pay (WTP) estimates of the use-value of an environmental good. Theoretical validity assesses the extent to which findings of a Contingent Valuation (CV) survey are consistent with theoretical expectations. Theoretical validity tests of a CV study carried out by estimating a separate probit function for payment principle question and a WTP function produces biased estimates.