One of the biggest challenges to measuring the environment is dealing with values that are not revealed in a market.

One of the biggest challenges to measuring the environment is dealing with values that are not revealed in a market. This has led to different techniques like the Contingent Valuation Method and Choice Modelling. Regardless of approach or method, an enduring problem has been that state-preference techniques like these give very different values depending on whether questions are presented as 'willingness to pay' or 'willingness to accept'. Explain why the values might be different and which gives rise to the larger environmental values